The blocks are not going to line up unless they are all close to the same size. Measure all your blocks. If they are all within an eight of an inch or so, you are all set, just pin the intersections as you go. If they vary a lot more than that, you have some decisions. One fix is to cut them all down to the size of the smallest block, however, this may impact the patchwork pattern, so you have to be careful. If just some of your blocks are too large or too small, you can unsew those and take a slightly smaller or larger seam.
There are 3 things that make your blocks accurate sizes:
1) accurate cutting and using the same ruler (or at least the same brand of ruler) for your whole project.
2) sewing with an accurate 1/4" seam for your whole project.
3) Careful pressing. You can distort your block if you iron instead of press, or you can press tiny creases where the seams are, which makes the block smaller.