Part of your problem is pregnancy. The quilt is fine but your judgement is off. In the grand scheme of things it simply can't be that bad. You said it's a crib quilt.
after a few spit-ups and other baby oops's you won't notice and crooked seams.
Now. lighten up and slow down when working on quilts. I also highly recommend pre-washing your fabric. The objective is to straighten the grain. It was woven correctly, but gets crooked from high speed winding on the bolts, etc. Then pay attention when cutting, also slow down. Like driving a car in a crowded lot, slow and steady is better when you are sewing the pieces together. On some things I use glue stick or very fine pins just to be sure they are lined up right.