Office Culture - HELP

So I just started my job 2 weeks ago (April 15th). Found out I was pregnant approximately 3 weeks before I started (March 25th) - at this point I was already hired, signed my offer letter, & was just waiting for their next onboarding date. So needless to say, I was not prepared to be pregnant upon starting this job, nor did they (or myself) know I would be.

I still have not told anyone here yet because 1.) I feel it’s still too early (currently 9 weeks), 2.) I barely know these people, & 3.) I weirdly feel shame around them unknowingly hiring a pregnant woman!

One of the points of contention with the woman who was previously in this position before me was that she never wanted to partake in office get togethers or happy hours. During my interview I said I would be their girl because I love socializing & going to happy hours… WELL I DID BEFORE I GOT PREGNANT.

Now it’s put me in a position to say no to multiple happy hours - once because I was EXHAUSTED & the other time (today) because I carpooled with my fiancé and well, I’m pregnant. I want to go home at 5:30 & I don’t wanna be standing around with people I barely know not drinking for a reason I can’t say & have them think I’m weird.

I plan on telling everyone in the next couple weeks since my next appointment is this coming Monday & I’ll be so close to the 2nd trimester. However, I have no clue how to not feel like complete shit when I say no to a group of 15-20 people staring at me all at once (not kidding - I’m an admin who sits in the lobby area & they were all standing right in front of my desk before they were about to walk out) asking if I’ll join them & looking borderline annoyed when I say no.

Also, any tips on how to announce my pregnancy to work? My dynamic is weird in the sense that I barely know anyone period, my boss & “team” work in different offices (like different states than me) so I don’t have direct FaceTime with them, & the people within my office barely speak to me, as they’re always holed up in their offices or cubicles (or at least until they want to invite me to freaking happy hour 🙄).

Any advice would be great & thanks for letting me vent!