I agree with others that it appears to be the block size. Sorry Hon. The first block looks fine with seams matching. The second block is definitely off and that should be a red flag. When you can't fudge and match seams you just need to stop and regroup. As you can see, a small mistake can be compounded enormously. Don't feel bad, I'm sure it has happened to every single one of us at one time or another. I know I've been there plenty.
I'm just editing to say that squaring each block as you finish it would have alerted you to a problem. Depending on the block, sometimes it's helpful to square each unit within a block. As a self-taught quilter, the squaring thing gave me fits at first as there is not a lot of info out there (or emphasis) on squaring, and there is a certain assumption that all will be square and you will know how to do this. So, my system is square each unit, square the block (seldom necessay if all units are square) square the top (seldom necessary if all blocks are square). I think you see where this is going :)