1. squats: go do all the way to incorporate more hamstring activation. variations would be jumping, one legged (or lunges), or both. there’s also different stances you can take.

2. push-ups: wide, narrow, explosive (pushing yourself off the ground for a second), and eventually one handed.

3. pull-ups: change grip from palms facing away to palms towards you. a more advanced technique is to stagger to one side, meaning pull more with one hand than the other.

if you can get your hands on some adjustable dumbbells, that’d definitely help. you can add deadlifts and rows to your workout.
References :
i’m a first year med student, and a health nut.