This is what i like to see bro. Members coming on here to learn proper form of an exercise. Props to you. Your range of motion will not be the same as your friends, someone else at the gym, any of us on this board. ROM depends on many factors, and the idea of 'ass to grass' is not the only proper way of squatting. Some techniques you could utilize....
(1) try out a wider stance. this should allow your body to carry further, compared to a narrower stance.
(2) drop your weight and get form down to a T. head up, back in a natural aligning arch, butt pushing back while descending, pushing off from your heals, properly breathing, position of the bar on your traps, not bouncing at the bottom, not locking out fully at the top, and so forth.
(3) Have someone watch you while you perform the movement and let you know on your progress to getting your thighs parallel to the ground (be careful your lower back isnt arching forward, especially the time you spend below parallel). Many times, the person doing a movement will think they're going low enough.... and they're really not. But once again, rom will be judged on an individual basis.
(4) Try putting a 10 lb plate underneath your heals. Not just to incorporate more work by the quadriceps but often people find it easier to go down when their heals are elevated.
So much you can do but most important is to know proper form of a squat (or any exercise for that matter) and practice it repetitively.... with weights you can manage all while using proper form