Hi so I'm really new to loom knitting. I successfully (ish) made a single sided scarf, and felt confident enough to try a blanket. I'm using the long rectangle loom, 21 1/2 inches. My problem is, I've youtubed, googled, pinterested, and looked in the direction booklet, but everytime I try to double side knit the middle of my loom squeezes together until it's touching. I thought I wrapped too tight so I undid it and restarted, but even when it's loose it eventually does it. Is this normal or am I doing something wrong?