Clearly, you have good color sense and will make an excellent quilter. do not despair.
When you are making seams cross, as in the 2nd picture, there is a simple trick. The seam allowance on the bottom seam should face towards you, the top away from you, so that the needle reaches the top seam allowance before the crossed seams. Pin there. By this method, the sewing locks the seams in the right position. A couple of years ago, my guild was doing a lot of blocks together. Several of the more experienced quilters had the exact problem you had here, but did perfectly with this trick.