Help on getting low on squats, looking for stretches?

I am looking for some stretches to help me a achieve a proper squat for weightlifting. Right now i get pathetically low, I can barely go down at all and I really need to achieve proper depth. This means getting my quads parallel to the floor. I've been trying to find stretches online but all of those seem to be for people who want to go further under 90 degrees, not people who can't get there. Right now what happens is after a not very in depth bend of the knees, as I try to get lower my upper body comes forward. I know that I can serisouly injure my self when my upper body comes forward. I'm looking to establish a nightly routine of stretches I can do that will help me achieve proper squat form.