Thank you so much for the comment! Hope to get your rating once it opens up for voting.
There should be the experience bar (some resolutions might f up the positioning a bit), but you are right that it doesn't show the amount you're still missing, just a bar that gives you some estimate.
We thought about the heal drops, but wanted to have the difficulty so that it might take few tries to get through level 1 to the boss fight. Also some replay value with having to try with different powerup combinations.