You’re running into acute fatigue problems squatting the same weight 3x/week. Vary up the load on those days, and you’ll likely notice better recovery.
When I started lifting at 18 years old:
- Max bench: 115 lbs x 6-8
- Max squat: 135 lbs x 6-8 (not even to depth)
- Max deadlift: lolwut
- bodyweight: 120 lbs
- height: 5'9