stitch in the ditch

Hello Maddie and welcome to the forum. I'm a novice quilter who experienced the same problem using a SITD foot. Before I bought a walking foot, which definitely solved the problem, I did a couple things to try to overcome the problem. First, I trained myself to keep my eyes focused in front of the foot as I smoothed and LIFTED the quilt sandwich. As others have mentioned, the weight of the quilt if it's in your lap is contributing to your problem. It must move freely. Third, I wore my kevlar gloves that I use when I slice vegetables with my mandoline. They have a grippy surface, and they provide just enough pressure to keep the fabric in motion at the correct speed. Fourth, slow down. You have to train yourself to coordinate all these concerns/movements. I hope this helps!

Edit: BTW the Machinger's gloves are a lot cooler in hot weather and far cheaper to purchase! I just used what I had at hand at first.