Ok, I feel really dumb saying this but what the hell...

I can't squat. I have never been able to and I have lived without it. Every now and then I try again, fail and give up.

Now I don't want to give up and I need some advice.

My problem is that I fall over backwards as I squat down. I thought that maybe I was using too much weight, so I lowered it. No luck. So I tried just the bar and still fell over. In the end I just tried standing there, squating down on my own without any weight at all, and I still fell over. (I can just stay up if I hold my arms directly out in front of me to move my certre of gravity forward, so with weight on my back, I have no chance.)

My balance seems to be fine. I can stand on one leg with my eyes closed and all that crap.

My heels always come off the ground and it feels like my calf muscles are too short to allow my feet to stay flat as a go down. So I tried to do it with a block of wood under my heels and I can do that without falling over. I guess I could do that for my squats but it doesn't feel very stable, and I heard that it is not safe. Is this true?

And anyway, I want to be able to squat "properly". What can I do?