It seems more like the character is "floating" instead of jumping. Ideally, there are two things to consider:
1. The character should lose speed as it gets higher, so that the player can have a visual feedback on gravity.
2. I've noticed it's complicated to switch direction and fine-tune the jump distance mid-air, which makes the jump very awkward, especially in a pixel-perfect platformer.
There are some guides and tips by acclaimed game devs on this, I'd suggest looking out for a Twitter thread where the Celeste devs talk about some of the techniques used on the game (I don't have a link to it right now). Keep up the good work, I'd love to see an update to this!