you mentioned you have done a few other quilts since and they seem ok......so you must be improving.....dig out the squares, and see what you can do now.......

Do you know someone who has been quilting for a long time?? Ask if they will "adopt" you for an afternoon to see if they can figure out where you went wrong. If you still have those blocks can they be trimmed to match the smallest block so you can use them?? Accurate cutting and consistent sewing is important, but you still need to measure the finished blocks to see if they need a trim somewhere. Sounds like you are getting the hang of it but someone to watch how you do things and offer help can be priceless.

In the meanwhile, if you think your blocks are not cut well, and you can't trim them up to make it work...I would cut out a mylar template, without seam allowance..center it on your pieces, then trace around it..that will give you accurate sewing lines. It's a pain, but may be the only way to salvage your pieces.

Important.....make sure you use the same ruler when cutting your squares.

Advice
 

I guess some of you are getting tired of my two cents. What makes a quilt a quilt is the quilting not the piecing. I have been doing this for at least 40 years. Before the early settlers in America starting making "patchwork" quilts there were whole cloth quilts for hundreds of years. Layers of fabric where quilted to give them body and warmth. Knights in armor had fabric that had been layered and "quilted" together to provide warmth and or added protection. Horses usually have a "quilted" pad under their saddles to absorb moisture and protect their skin etc. Woman often had a "quilted" petticoat under their floor length gowns that was quilted for warmth and to protect their modesty. Patchwork grew out of necessity. Fabric was mostly imported to America in the beginning. That made it expensive and precious. Woman were very careful not to waste any of it. Thus piecing was born. If you have to make due at least you can try and make the results attractive. Piecing has become it's own art form. What makes the "pieced" fabric a quilt is the actual layering and connecting together the fabric either by tying, machine "quilting" or hand quilting. I make at least 20 Linus "quilts" every month for our local chapter. At least half of them are made from preprinted " faux quilt panels. I find colorful childish prints and panels and layer them with batting and a flannel back. If the panel is to small I add borders to get it the right size. I then machine quilt, using a decorative stitch around the designs on the fabric or just every 4 inches or so across and around the outside border. I make those quilts envelope style. That means that the flannel and the print top are layered right sides together and then laid on batting. The three pieces are sewn together on three sides and then turned like a pillowcase. Then all I have to do is pin baste the bottom shut and pin every four inches or so before doing the simple machine quilting. Hand quilting can be totally portable. It is also something you can do while watching TV or having a conversation with friends and family. If I had to "create" every top I have quilted by sewing together possibly hundreds of small pieces of fabric I would never have made the several hundred quilts I have made. Find the part of quilting that you enjoy most and do it. Good luck and welcome to our world.

starch your pieces before trying to cut them again. you can starch a couple of times and straighten them as you iron. then recut at a slightly smaller size. the "purple daisy" has a video on preparing fabric. I always starch at last twice it really helps.

Another thought is that the actual size of your is not important, the important thing is that your completed block is the right size. Double check to make sure that if staring with 2.5 pieces after stitching you have a piece that is exactly 4.5 inches. If not adjust your seam allowance until you do get exactly 4.5 inches.

I wonder if your pieces have been stretched out of shape after having been sewn and ripped out a couple of times? Combined with your original cutting may not have been accurate, I wonder if the best thing is to toss it and just move on. Chalk it up to a Learning experience. The frustration is just not worth it sometimes!

This is a nice essay

I struggled with my very first quilt too.....it was a spiderweb star pattern. I took it apart several times, but was to stubborn to give up. Which was a good thing, if I had given up on it, I probably would have ditched quilting altogether. I agree with someone that said set them aside for now......you may just figure out what you were or were not doing that kept it from fitting. Sometimes I have to walk away and do work on a different one and then I go back to it and it's a "DUH" moment, when I figure it out and realize I was making it harder than it needed to be. Good luck with whatever you decide!