I found the missing cats, got 9 hearts and I think(?) all of the upgrades and boss fights. This is a very well done minimalist metroidvania.
The boss fights could have used a touch more complexity, but I'm not going to complain too much about it. I will say, the music loop did get a little annoying after a while though. A second regional song, would have helped a lot. I know it goes against the spirit of metroidvanias, but a checklist of content might have been nice for the jam in specific, just to be sure people don't miss your hard work!
All of the upgrades felt really good to use and natural to the character and the location. The gameplay was smooth and fun. Exploration felt natural, but your limited tileset works against you to some extent because some areas end up looking similar, though I can tell care was put in to try prevent that. Well done!
Also, noticed a small (heh) bug where you can duck and not be hurt by spikes. It felt unintended because it wasn't explored as a mechanic.
Also also, I missed that there was a map button and beat the game without it lol! I just found out by reading the other comments!