Buy some fish material, looks like you need some color.
Cut strips of fabric and put between the blocks, any block of a different size add a strip to enlarge, the blocks will need to match at some point to sew them together.
After getting your horizontal rows matched/together, then start the verticaql rows, do the same thing. Adding strips of fabric, adding sashing to enlarge small blocks.
Add narrow strips, wider strips, whatever to get the blocks lined up so you can sew the rows together.

I just did a top that I had to make work. Different size borders are great for these things. They will actually add a great feature when all together.

Since you've pp'd the fish, why not do the same for the sashing? At least to get the size of pieces and layout of pieces you'll need to connect the blocks. You can lay out the paper parts to make sure seams intersect where they look best before cutting into fabric, which could be done just by measurements at that point if you'd prefer, or by finishing the pp'ing. With the staggered blocks you may not want full length vertical or horizontal seams in the sashing anyway.
Then bind in at least one of the other colors in the pp'd fish.

This will be just like putting a jigsaw puzzle together. This is how the "funky" swaps end up as we do all different sizes of blocks.

You will want to make "sections" to avoid doing y seams. Lay out the blocks as you want...(you've already done that). Measure all of your blocks, then figure out what size "fillers" you will need to fit in between them to result in the finished size you need. Either sew some pieced blocks in that size, or just cut some plain fabric filler strips to fill in the "holes". These make such great quilts! Yours is going to be great!

I saw this technique talked about in a quilting book a long time ago, and it just makes the blocks look like they are picture framed in different size frames, then after these adjustments are made the blocks will be uniform. Try auditioning the blocks with some folded scrap to get an idea. :-D

This is what I was thinking Also get your hands away from the hair--- bald spots are never a good look

I agree - add borders around each block to make them all the same size and then join with sashing in between the blocks.

Not being very long in the hobby of quilting, you could maybe put the blocks together with sashing and background that work without stress, and then maybe applique the blocks that are giving you a hard time with the math? I did this with a penguin quilt that didn't quite turn out how my graph paper and I imagined, so I just appliqued the rogue blocks to the top, and they look so amazing! Like I had planned it that way (hahahaha!). I think the fish you have lying on your tabletop are gorgeous, by the way. Just let them flow!

grid paper is best to figure these things out. get some and start drawing what your quilt size is and where you want your blks to go and you will figure out the measurements that way.

Get the graph paper out. That is the easiest way to start figuring your placement. I do the blocks one at a time in order for that row and cut each sashing piece as I go so I don't get mixed up and have even more mismatched sizes. When all the blocks in that row are the same size I stitch it together and go to the next row.