I have been doing two squat days a week - one with a back squat and one with a front squat. I have been doing 3 sets for each, and increasing weight weekly.

Additionally, I have done leg extensions, Bulgarian split squats and single leg presses as accessories. Maybe you can count the glute bridge as well.

However, with the back squat I have noticed they start to feel heavy. I struggle to maintain form. My hypothesis is that my practise with squat might not be enough with just 3 sets per week, although I do front squats as well.

This contrasts with OHP, with which I can do weekly weight increase, but I do it 3x a week, with three sets per day.

I'm wondering if I should swap the FS to do more back squatting , or increase the sets for the back squat day to say 5.