Back pain from squatting with long femurs

[bclark98]

Hi everybody. So I've been squatting for about 2 years now, but have been unable to make solid progress due to lower back pain. The problem is I’m 6’1 and have extremely long femurs and a short torso so it makes the squat very difficult. As a remedy, I've raised my heels on a pair of 5lb plates and have been able to maintain an upright position and a neutral spine throughout the squat yet I still have lower back soreness after the workout. I have a picture of myself at the bottom of my squat included in this post so let me know what you guys think of my form.