Tell them?

Mimi
Okay, so I need some opinions. My SO and I are going out with my BIL and SIL for a nice dinner tonight. We haven't told anyone (except my mom) that we are pregnant. I'm 12+ weeks but our plan was to wait until we had the doctor's appointment this week to tell our families. Both telling them "early" and not telling them tonight makes so anxious. I feel this guilt because they've been trying to get pregnant for over a year. I know my SIL is on the lookout. She even commented on me not drinking at Christmas. I'm not a big drinker, but I'd definitely be having a glass of wine at dinner. So what should I do? Tell them or wait? Sorry, I know this is so stupid!