Childhood surgeries and squatting problems (Advice needed!)

Hey guys!

I'll try and make this as concise and informative as possible so you can help!

I was born with double club feet and underwent over 6 surgeries, 10 years in plasters and plenty of time in wheelchairs as a kid. Suffice to say I'm not starting on the same spot as most others and I'm looking for some specialized advice!

Due to all the surgeries, I have the following issues;

• my Achilles' tendon is super small and tight even after years of physio. As a result, I tend to walk around on the balls of my feet just like a boxer
• my calf muscles are exceptionally small and quite weak (I've been told This is a result of the surgeries and I will never be able to develop them any meaningful amount)
• the bones in my feet and ankles were all pinned and fused together. As a result, I have quite literally next to no mobility at all in them

I am a 24M and have been lifting for about 6 months now, predominantly the big 3 and accessories. I currently weigh 75kgs and am 6"1 for scale.

My squat is compromised as I obviously lack the mobility to force my knees forward and squat without immediately lifting my heels off the ground. To compensate for this I put 2.5kg plates under my heels (an act that I feel makes the lift harder just to maintain balance). I have also been told to simply widen my stance to the point where I can perform the movement, but this resulted in me spreading my legs wider than a sumo deadlifter and having a tiny ROM.

My other lifts have vastly improved (deadlift mainly due to my back strength increasing rather than legs as I also have to put plates under my feet to perform the lift), but my squat remains at quite a low weight.

I have tried working leg extensions, leg press, hack squats, stiff legs and hamstring curls and still struggle very much with the lift.

I'm hopeful someone around here might have some suggestions that can help me with the squat! Whether it be accessory exercises or perhaps a tip to make sure my heels stay flat whilst I squat!

Thanks guys!