Hang in there
A great way to learn to squat upright is to do squats facing a wall.
First, you need to go over a few points of form :
1) Shoulder blades should be pulled back and down. Always stretch your pecs before squats so you can comfortably get in that position.
2) Get a lot of motion through the hips. When you descend do not think "bend knees", think about doing an anterior pelvic tilt. On the ascent do not just think straighten legs, think about thrusting your hips forward.
3) Always keep the chest high. Pretend that there are rays of light coming out of your nipples (I know this sounds gay/ridiculous, but stay with me). The rays of light should be parallel with the ground. If the rays of light would be lighting up the floor out in front of you then you are leaning too far forward.
4) Look straight ahead, perhaps up slightly as you descend.
Now, get a broomstick. Trust me on this one, you want something very light but as long as a barbell. An empty barbell will be too heavy to start.
Face a wall with your toes 6 inches (maximum) from the wall. Place the broomstick high on your traps. shoulders down and back, chest up high, and descend into your squat. You may feel uncomfortable at first, you may also feel uncomfortable because you smack your forehead off the wall
Persevere, as your technique improves you will be able to squat to full depth. Once you are able to get deep then do a set of 20 reps or so to really lock the pattern in. Next, squat down into the bottom position and hold it until failure. Keep the shoulders back and the chest up! Weight on the heels! Stay low! After a minute or so your quads will be burning somewhat, but I have a sneaking suspicion your lower back will be in more pain.
This drill teaches one how to squat upright and strengthens the lower back. It forces you to maintain lumbar lordosis and although it may feel like you are hurting your back you are certainly not. You are strengthening your back so that you go deep, stay upright, and avoid injury.