I used to be cool with this manga..then I grew up and realise words like "mom" and "wife" ...

I think you’re looking at it the wrong way. “Mom” and “wife” here literally means who gave birth to the baby. Even in a female-female omegaverse relationship, the one who didn’t give birth is “dad” and the one who got pregnant is “mom”. Simple as that

that's still heteronormative my guy. It could be dad and dad and husband and husband. There's no reason to say husband and wife when talking about 2 men. And what's yuri got. To do with this, it could be heteronormative too. Also the people who created this are straight and most people who read are straight girls. I'm a bisexual guy, who has done his research. So I think I know what I am talking about when talking about hetero norm.

What I don't understand is why you're making a big deal out of it?

Cause it's annoying and damaging.

I don't think a fictional world where anyone can get married with anyone and then have babies can be all that heteronormative, no matter which words they use. I'm pretty sure that the actual family dynamics are more important than words like "Mom" or "Dad". If I was in a lesbian couple and my partner had a kid, I wouldn't mind being called Dad. Sure they could use word "partner" when talking of each other.

This manga is really wholesome and sweet. It depicts a fairly healthy relationship between the two parents, and the family as a whole is simply adorable. I wouldn't call it "a straight relationship in the skin of a gay one" just because of the words they use. If you take issue with them not being "masculine" or "realistic gay" enough, we could have a discussion about it. There are many yaois where one of the guys acts in a way that is fairly typical for a traditional shoujo heroine. This is not one of those.

Also I'm a bi girl and I've read gender studies at university level, if we need credentials to discuss Omegaverse manga.

+ as you said yourself, this is a sexual fantasy for girls. The point of yaoi is, more than depicting a realistic gay relationship, to exist as a fantasy. Like romantic and erotic stories in general, it's intended to excite. It's technically good if the relationships (whether straight, gay, lesbian or other) in stories we read are healthy and ideal, but some people just feel more titilated by more twisted stories. We go deeper in the realm of fantasy with omegaverse, which has the added fantastical elements of alphas, betas, omegas, pheromones, fated partners and mpregs. "Annoying" and "damaging" are words that can be used to describe pretty much any form of erotic fiction, and definitely omegaverse as a whole. So while it is important to have these discussions, you are making a big deal out of it.