Very fun game! I liked the different mechanics of the two sizes. I also liked the level design a lot. In most cases I knew pretty quickly what I needed to do. Well except in a wall jumping section in level 1, I struggled a lot to understand what I needed to do, only to realise that it was a skill issue on my part lol. Maybe that kind of section should be easier, or it should be later in another level. I did get to beat it after a while.
In the second level I enjoyed the realization that size changer lasers/gun work on the enemies too. I didn't get to finish level two, there was another section that was really hard. Still had a lot of fun tho, its a very nice game with a cool concept.
In a game jam balancing is hard to get right, so my feedback would be that if you are making a jam game, you should try to balance it on the easier side of things so that most people can get to the end of the game and see all the cool stuff you make.
Nice work!