I have been stuck for 2months on the same max weight of 90kg for one rep.For 5 reps I am stuck in 75kg for 5 reps.As soon I increase weight to 80kg,my reps count becomes 2-3 & after that form being to break.I sort of tire out and I tend to need help at the bottom point to do the remaining 2 reps.This has been the story for several weeks now.Other than squats I do other exercises like press,lunges, Bulgarian split squats and extensions for 8-10 reps.Anyone has any tips or ideas or even a leg routine for my case ?Also I do Deadlift on back days and the progress is OK, currently I can do 100kg for 2 reps.I think I will try to go for 3-5 reps @ 100kg this coming back day.I really need to my squats to catch up. I am 168cm at 62 kg.
If you've been stuck at the same weight for a couple of months, then you've definitely hit a plateau. There are a couple of planned ways I've used to break through plateaus before, and one bonus accidental way.
Reduce the weight you're squatting and start to build back up slowly. I'd highly recommend Jim Wendler's 5/3/1 for this approach, but what should work is to drop your squat weight to about 80 - 85% of what it is at the moment (so, say 60kg for 5 reps), then add the smallest increment you can each time (usually 2.5kg).
Assuming you're squatting once a week, and you increase by 2.5kg per week, it'll take you 8 weeks to get back to attempting 80kg for 5 reps. During those 8 weeks, you shouldn't really be missing any lifts since they're mostly below your current 5 rep max.
Squat every day. I've used this in the past to great effect to break a plateau and improve my squat technique. The idea is that you take a sub maximal weight (so, I'd say 65 - 70kg) and every day work up to a couple of sets of 3 reps at that weight. Note, 3 reps, not 5. This is sort of akin to Pavel's Greasing the Groove technique, it just gets you a lot more comfortable and capable of squatting that weight as well as squatting in general.
Once doing that weight for a couple of sets feels comfortable (I did I think 3 weeks of a couple of sets of 3 reps at 70kg), then bump up the weight a little and carry on. When you're feeling good, test your max again.
This method is more of a "by feel" method since there's no definite progression, it more relies of a lack of ego lifting and the ability to just get in and do the work without thinking about it too much. It also helps some of the psychological issues people have with throwing a heavy weight on their shoulders and squatting with it, if you've done something every day for the past 3 weeks, then it doesn't seem as big of a deal as psyching yourself up to do it once a week. Which brings us to...
Bonus Method 3
By accident. Following on from the end of the previous method, some people just hit a mental block at a certain weight. A friend of mine was stuck at 120kg for 3 reps. He'd been stuck there for a good month, when he tried 125kg, he got one very shaky rep and any higher bailed the lift. One session, we were chatting about nothing while he was loading up the bar, not paying attention, he un-racked it, stepped back and hit 3 solid squat reps. THEN someone pointed out to him that he'd mis-loaded the bar, and what he thought was 120kg was actually 130kg.
From that point on, he managed to hit 130kg every time.
All of these methods are presupposing that your squat technique is solid. It might be worth getting someone knowledgeable to critique your technique and if there's any issues, fix those before pushing up the weight.
I'd personally keep in the assistance exercises you're doing (except for leg extensions, I've got nothing good to say about those), but also throw in some more lower back work on squat days, in the form of back extensions, reverse hypers or good mornings.
- Eat more food, especially protein, so that you can increase your bodyweight.
- Reduce your squat work-weight increment from 5 kg to 2.5 kg. The stronger become, the smaller your increments must become.
- Remove lunges, split squats, and extensions from your program. You don't need them, if you're squatting and deadlifting. Please consider the Starting Strength program, which can help you determine appropriate work-weights and frequencies for these exercises.
In response to your "need help at the bottom point to do the remaining 2 reps": Don't do this. If someone else touches the barbell then it's not your rep, and you should not count it; otherwise, you're just fooling yourself, and you'll have no objective way to quantify your work.