OP, you seriously deserve better. Warning: I am merging the two posts in this comment. She thanked you taking care of the house you live in, too? Manners 101. No one wants to live in a dirty home. If dishes are piled up in the sink, they need to be put in the dishwasher or washed. If the floor is sticky, it needs to mopped or pull out the Swiffer. If laundry is piling up, it is not just one person's responsibility. Are you just supposed to ignore the child if she needs food or something? What was the "thank you" for exactly? For being human and not wanting to live in a dirty home?
I know it is hard to ignore when your ovaries are twitching and your bio clock is ticking, but this situation sounds awful. I would not bring a child in to a situation like this. I had to go back and read your intro to see that you are in a poly-fi triad. I was going to suggest opening the relationship and you seeking someone else to date. Your girlfriend is already dictating how you are going to raise the child that you carry for 40-42 weeks, push him/her out or undergo a C-section with, and telling you, that as the biological mother, YOU do not get to be called mum/mummy/whatever. Your baby will be taught to call you emaw or emmaw, like their daughter calls you. She wants the child to grow up thinking he/she belongs to her and her husband. I think you said that you are out to her/your family but not publicly? Is your family not close to you like distance wise? Would they not wonder what happened to your child if you were heavily pregnant but not producing a child at family gatherings? I am just trying to figure out how they are going to pass a child off as theirs. Is your boyfriend going along with this? Why would you even be willing to discuss this? Because you love them and they claim to "love" you?