"love is an illusion" is a classic centered around mpreg. It's an omegaverse. Go for it.
There's also "smryna and Capri" which has the best mpreg plot ever with green flag characters. I'd vote for this mote
Hosik's story: my favourite because you literally can see him from tiny bumps to big bumps and even breastfeeding. Love that so much
The serpent seduction: this is also similar to hosik's. Can even see the male lactating
Heat and run: honestly for this one you dont really see them with bump since there is time skip but there is few chapters where they show it
Love is an illusion: no breastfeeding but there is some bump bump there
Surge looking for you: theres bumps and even mild breastfeeding. Mild because the uke has a hard time really produce milk. Low supply ya know
The tigers den: a lottttt showing of bumps, even the kicking, the lactating start during the pregnancy. Shows it very well
Prison breakfast: shows minimal bump since the uke is quite small so the bump is also quite small but very cute
Wolves behind bars: shows bump but after the baby born the manhwa ends
Blood link: shows the pregnancy, the birth heck even the c section scar.
How to snag an alpha: time skip but there is a bump
Waterside night: well there is like how he went through the pregnancy, the bump is very timid
Dirty desire: bump shownnnnn very cute
Dog and birds: there is a part where the uke kinda sad that his abs gone because he's pregnant but the bump wasnt big enough but i hope it counts?
Like a fever dream: oh this one definitely shows
Into the rose garden: i wouldnt recommend reading this if you want the fluffy cutesy bump because this story wrecks me
If its not fate then what is it: this one is still ongoing, ive read the korean version one and the uke will definitely have a bump later on English version/ translation. The uke will also wear pregnancy clothess
recommend me some good yaoi where mpreg is the plot, bonus points if u can actually see the baby bump