Very Weak:
1) It's multiclass
2) It's situational (Darkness)
3) Pretty easy to fail on Stealth Checks.
4) You expend ALL until a short rest.
You have 3 feats. You can't Expertise in Stealth.
Gloom Stalker:
If you take the Attack action on that turn, you can make one additional weapon attack as part of that action. If that attack hits, the target takes an extra 1d8 damage of the weapon's damage type.
Your damage is: 6d8 (27 damage) + 6d6 (21) + 7d8 (31,5) + 90
If all hits 169,5.
If all hits.
But, +6 to hit vs 23 AC (18 AC + Shield Spell).
20% chance to hit = 32 damage.
If you are on Darkness (Situational)
You average damage is 80.
After nova. 32 damage per turn (If all hits). The Sorcerer can still blast the enemy for 1 minute. Dealing upcasted Schorching Ray for long time.
The sorcerer is clearly superior. And he is still a caster.
When you place a Multiclass and darkness situational, you have already lost. Go without Multiclass