V.A.
Hi C.! Congratulations! I stopped at 4, because I just knew that I would keep having more, if I didn't have a tubal, but I had 4 children before I turned 27 all 1 year and 1/2 apart, and yes people are going to react "You're pregnant again!?", or "Buy a t.v.!" Or something along those lines. It happened to me anyway. But don't concern yourself to much with that. Children are truly a blessing from God and I know your mom might not be too excited when you tell her, but when that beautiful baby comes, well, you know how Grandmas get :)
I would recommend telling her now so she has time to prepare her mind for 5. It's also better for your relationship to show her that you want to be open and honest with her.
Take care and may you keep God first!
V.