[MENTION=6803713]Slit518[/MENTION] I appreciate what you're attempting, but it's a bit of a mess.
1) First, there's no clear conceptual underpinning. "Witches are all different..." "Where they get their power is a different story" OK, apart from that second sentence being thoroughly awkward English, I've taken away nothing from these sentences about what a witch actually is. Compare your opening "identity sentence" to that of the PHB Bard:
[SECTION]Whether scholar, skald, or scoundrel, a bard weaves magic through words and music to inspire allies, demoralize foes, manipulate minds, create illusions, and even heal wounds.[/SECTION]
Even the Bard, the most jack-of-all-trades D&D class, has more coherent identity in that sentence than your witch. My #1 recommendation is to go back to your design notes and create a coherent "identity sentence" for your witch class that meaningfully distinguishes it from the other classes in D&D. Why should witch be its own class? I'm not convinced yet.
2) You're walking into some very nebulous territory including a drawback built into a class – 5e very deliberately avoids doing that. Also, thematically, the idea of making a sacrifice for power skates very close to the Warlock's wheelhouse. And finally, even if I as a reader manage to accept "yeah, ok, so in this guy's world witches are about sacrificing for power", I'm faced with conditions that totally shut down my witch character...
If I'm blind, that shuts down a huge amount of spells. If I'm deaf, you have me making Concentration checks just to cast spells with verbal components (hint: that's 99% of spells). If I'm paralyzed my options are...have a donkey cart in the dungeon? Maaaybe soul-less is an ok sacrifice, but that outright treads on the Warlock's thematic wheelhouse implying a bargain with an entity.
If you insist on going this direction, have a look at Pathfinder's Oracle class to see how they handle classic tropes like "the blind oracle."
3) Origin of Power... So how is Power of the Cosmos, which you describe as "alien", different from a Great Old One patron for Warlocks? How is Power of the Oceans different from a Storm Sorcerer? How is Power of the Heavens different from the Celestial patron for Warlocks? How is Power of the Hells different from The Fiend patron for Warlocks?
There's enough ambiguity between Sorcerous Origins and Warlock Patrons, that adding a *third* class with something like that is just too much. Moreover, if you look at witchcraft traditions from Europe (the ones many gamers seek to have in mind when hearing "witch"), they often were/are synergistic, blending a mix of techniques and religious/spiritual beliefs. They might be thought of as occupying a strange niche between sorcerer, wizard, cleric, and druid. So "Origin of Power" probably isn't as relevant to that conception of witchcraft. Where does a witch's magic power come from? The answer to that might be: anywhere he or she can get it.
4) Coven is the most identifying feature you've included in your witch class. "Coven" implies a gathering of like-minded witches. That's interesting! Only the Druid alludes to a society of druids by including the Druidic language; but "Coven" has the potential to outright make a society of witches part of the class/game. However, instead you solely make it the vehicle by which to give the witch some extra spells. Eh. That's kind of lackluster and definitely doesn't take the concept in the creative direction it has the potential to expand in.
Also, including scaling Origin of Power and scaling Coven features feels a bit redundant.
One possible interesting direction to take "Coven" is to augment the witch's spellcasting when they do some kind of circle magic with other spellcasters, or have non-spellcasters providing an offering of some kind (blood, gold, food, a dance, a song, lock of hair, etc).
5) Spell List. If you want to get really clear about what a witch is, creating the class spell list could help. For instance, witches could easily be imagined to cast charm person, cure wounds, and call lightning! They could easily break the usual divide where arcane-casters get fireball and divine casters get cure wounds -- so you'll want to put some thought into what spells a witch *shouldn't* get, which spells would be *outside* a witch's wheelhouse.