Lifting form and progressive overload question

Basically, is it better to focus on how much weight I can move or keeping great form and doing full range of motion? I'm currently focusing on form, here are details:

I've been lifting for over a year off and on and am finally starting to feel at home in the squat rack. I've noticed my form tends to go out the window when I move up to heavier weights so I've been doing this weird combo of BBB and SS which is 3 sets of 5 at a heavier weight [like hard to do the 5th rep] and 5 sets of 10 at a lower weight [still difficult to do the 10th]. My current goal is to keep cutting very slowly and lower my BF% over the rest of this year. I eat more on workout days and maybe go for a jog once a week, otherwise it's just 2 miles of walking to the gym and back, plus gym 3 days a week where I alternate between Bench/Squat and OHP/DL, plus 6-8 sets of ab work [planks for 90+ seconds, leg lifts, reverse crunches, et cetera]

At the lighter weight I can do bench to my chest and back, deeper squats, better control on OHP and my back doesn't bow on deadlifts. I'm not increasing the heavy weight because I don't like how my form can change to compensate, so I'm instead trying to get to the point where I can do 3x5 at the heavy weight with the same range of motion as my 5x10. Does this seem like an okay plan or will I just stall out and not see any real progress? I figure if I'm able to move the same weight easier and in a fuller range of motion, that should mean strength has been gained, right?

Again I'm not trying to gain weight or serious muscle, more just get better control over what I have and keep it as I lose this last 10 pounds slowly, like 1-2 each month. I don't really have time to do more than 3 days a week and sometimes don't even have time for that, I just want to make sure my form is rock solid before I start really increasing the weight and move into something like 5/3/1.

Thoughts?