D&D 5E Quick fighter Mystic - Help and tips

Hi there. It's been ages since I last posted on this forum but I kept lurking and now I come to you in need of advice.
Yesterday, sadly, my cleric died in front of an execution squad, along with the warlock of the party, and now I'm thinking of a new character. I always wanted to try the Mystic (the UA one) and I came up with something after tinkering a bit. I don't care about min/maxing but I like my characters to be good at what they do. The party is composed of a Dragonborn paladin (conquer oath), an Elf Fighter (arcane archer), a magician of some sort (the warlock player only likes magic users, we still don't know what she's going to do) and a Goblin Artificier (he's probably going to change too into a rogue or a wild shape druid).
The adventure is kind of railroaded and focuses on defeating an undead menace, in a grim medieval (and not that much fantasy) world, brought by demons and corrupted inquisitors. Mostly we encountered demons, humans and undeads.

But let's talk about the character: I was thinking of a melee character, with good mobility, some crowd control (not that much, just a sprinkle of it) and the ability to burn stuff, just for the fun of it. He loves fire XD That's what I came up with:

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Name: Khitan Firesoul (probably will change)
Race: High Elf
Class and Level: Mystic 5 (Immortal Order) / Ranger 1 (Using the UA variant)
Background: Urban Bounty Hunter (SCAG)
Stats: Str 8 Dex 18 Con 16 Int 14 Wis 12 Cha 8
Skill Proficiencies: Athletics +2, Acrobatics +7, Stealth +7, Insight +4, Perception +4, Survival +4
AC: 17, Init: +4, HP: 47 (I took the average but next session I'm probably going to roll because I like to gamble XD)

FEATURES: - Psionics: 27/27 Psi Point, Psi Limit:5- Mystic Order: Immortal (Immortal Durability: AC= 10+Dex+Con, +1 hp x level, 2 temp hp at the beginning of each turn)
- Mystical Recovery
- Telepathy
- ASI: +1 Dex, +1 Cos
- Strength of Mind:


- Favorite Enemy: humanoid: +2 damage, advantage a Survival and Int skills to recall information
- Natural Explorer:
- Ignore difficult terrain
- Advantage on Initiative checks
- During the first round advantaged on hit rolls against creature that haven't acted yet
- Plus all the usual stuff for travelling for an hour in a terrain

DISCIPLINES:
- Bestial Form: I took it for the animal forms: bonus AC, advantage on perception and flight in primis (no concentration required). The damage ability is good but redundant with other disciplines
- Brute Force: A different kind of damage ability but I took this discipline mainly for the chance to push enemies and the super jump (my previous character was killed by archers to high to be reached. Never again!). The bonus on strength checks is nice.
- Intellect Fortress: plenty of magic users in the campaign, so bonuses to saving throws are always welcome. Being able to give disadvantage as a reaction helps me with durability.
- Nomadic Step: this I took for mobility. Various ways to teleport myself and my companions seemed a good deal. I don't understand the value of the anchor but it's ok.
- Mastery of Fire: this is a BG choice^^ My elf is a pyromaniac so I HAD to take Mastery of Fire. Plus it gives me some nice AoE option and a sort of armor that deals damage to enemies in close combat, so not a waste.

Equipment: no armors. Rapier and shortbows (plus stuff)
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And that's it. My idea was to have a good quick fighter, (nomadic step gives me movement, brute force gives me damage and pushes) able to track people (we really needed a tracker up until now), with good endurance (AC 17, that can become 19 with animal form, plus the chance to give disadvantage as a reaction, plenty of HP and 2 temp hp each turn, good bonuses on saving throws). I like what I've done so far but I have some doubts. Mainly about the Ranger Level (I took it for flavour and tracking reasons, plus the advantage in initiative): is it worth it? I'm loosing 5 psi point and I will have to wait 2 levels instead of just one to get a 6th discipline (plenty of interesting stuff) and 6 psi point limit.
I also have doubts about the diciplines: mainly Bestial Form and Brutal Force seem somehow redundant (but I also need 2 Immortal Disciplines and they're the only ones that really interested me) and I'm not sure about Nomadic Step (yes, it's a lot of mobility, great mobility, but is it too much? Is it worth it?)

So fire away and feel free to destroy my build if you want^^ I'm looking for tips to improve it.

Perhaps changing out Nomadic Step for Mantle of Fury or Giant Growth. This is mainly because you can use brute force's Mighty Leap as your main mobility increase (doesn't take any actions), and you don't have many abilities that use concentration(besides the Mastery of Fire stuff). So if you want to help buff the party more you could take Mantle of Fury and use Aura of Bloodletting which I think is OP. Or take Giant Growth which would increase your melee damage which may be falling behind a bit. Besides that think it looks good!

i've been toying with various variations on what you posted for a while (not usually for 6th level more like 9-10) I would say that your stat focus doesn't mesh well with a mastery of fire type. you'd be better to swap int and con to give you better spell saves, but also mastery of fire isn't terribly melee friendly with the exception of fire storm. if your plan is to basically to jump into heavy melee pop firestorm and start swinging ala "Flame on!" then that could be fun and you don't really need int. otherwise going Wu jen for tasty lvl 6 ability to grab elemental weapons (for your fire theme), talents Beacon (look like you are always wreathed in fire!) energy beam shoot fire beams, mind slam (prone is awesome), if you are allowed other ua content, having 3 levels in ranger for primeval guardian is pretty sweet for a burning bush look. with an extra 1d6 on hit, reach and 3 temp hps per turn (to make up for those lost by not being immortal), but i would get level 8 min and probably lvl 9 in mystic before going into ranger unless you really like the initiative boost or want to wear medium armor, the extra disciplines + 1d8dmg plus lvl 5 (7 psi) spells is pretty tough to pass up/delay

Nomadic anchor is awesome because you don't need line of sight. drop anchor outside door before going in, or in a box,if in trouble teleport out of the room, or into the box to hide.