I am really stuck on the left hand in measures 17-19. If you can have a piano at hand or imagine you have one in front of you . . . that would be superb

So in the image below, the part colored red is uncomfortable; the thumb has to come back fast and cover some distance. This is especially annoying in the second red section. I can play all of it, but it comes out uneven, in volume and a little bit uneven in rhythm.
The blue section is very nice and comfortable for my hand and it works.
Should I keep the fingering and hope that when I finish the piece and master it that it gets more comfortable, or change the fingering? If so, can you provide some options?

Thanks,
Esteban