https://www.mangago.zone/read-manga/puchitto_hajiketa/
Ashitaka’s an out and proud gay man, trawling for booty calls at his favorite gay bar—but only bottoms need apply, because Ashitaka only tops! His first attempt at gay sex three years ago ended painfully and embarrassingly, and he vowed to never yield his ass to another man again—but fate has decided to throw the very man responsible for his ‘bottom trauma’ back into his life, and the guy’s looking for a fresh start.
https://www.mangago.zone/read-manga/neko_x_neko/
During his high school years, Keita was slender and had feminine features, but he fell in love with Satoshi, an upperclassman who had the lean, masculine physique he dreamed of. Keita confessed and perhaps due to his beautiful, girly looks, they started going out. Three years later, their relationship is as strong as ever, and they currently live together like newlyweds. However, there was one big change...! Keita had matured into a manly guy! Because Satoshi used to be straight, Keita begins to wonder what his boyfriend thinks about the situation, even when they're having sex...
https://www.mangago.zone/read-manga/like_a_tidal_wave_from_pheromone_shower/
Omegaverse story. A world where men can also get pregnant. Suh Lim, an alpha-looking omega ended up with a gambling addict alpha, Hae-Il after being kidnapped due to his relation to his family's company: Chungang corporation. He hid his identity as an omega but what happens when Hae-Il finds out?
https://www.mangago.zone/tag/seme%20to%20uke/?page=1
This is where I found some more manga's similar to what you want
wow! thanks for the recs and explanations :D
I hope you enjoy reading them
Looking for recs where fixed top turns into a bottom, also I’d prefer if he was not skinny and short like the stereotypical bottom, ty :)