Wohoo! Finally got them all. Fantastic mechanic and level design!
Do you have any hints for levels 9, 10 and 11? I'm absolutely stuck.
9: you are handicapped the whole level because you need to get back to that 1x1 in the upper left, and so you need to leave your initial portal open the whole time. You can only push the white blocks and not use portals. You need to get two white blocks into a configuration:
(or maybe it's flipped) by only pushing them. Use the yellow Ls to help push around the white blocks.
10: This is actually far simpler than it seems. It seems like there are a whole bunch of things you need to do, but if you just get to reconfiguring the long yellow blocks to be horizontal, then push them into the water, you can get around the map pretty easily to solve it. You don't need to be too conservative with the white 1x1s, but where you push them ends up being straightforward and pretty simple (there's a bit of portaling but it's not too complex). I think in the end I might not have even used one of them.
11: It's been a while and I'll need to reconstruct what I did :). I think you need to use the white block and the long L to push around the short L to get it into place, and as you may have guessed the white block needs to have a portal through which the long L block will protrude upwards into the 2x1 slot but that is the really tricky bit. I remember I spent a long time playing around with portaling at the two white slots at the top, as well as trying to get the player character above the midway river to manipulate things directly; I think that the solution ended up involving neither, but I don't remember for sure.