nervous to announce my pregnancy.

So my husband has two kids from a previous marriage that we have full custody of. I gave birth to our first baby together last October. I found out recently that we are expecting another. I'm nervous to make a big announcement because both of our families said we should stop at 3 kids because that's enough. They said if we were smart we would stop at 3 because if the price of having kids is too expensive. It's not like we can't afford it. We wouldn't plan a child without being sure it was the right decision. I didn't want to put my dream of having two kids to the side just because he already had two kids. Now I don't know what to do or how to handle it announcing.