Long time lurker, first time poster

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I'm a FTM, first ever pregnancy (took awhile to conceive... DH and I are both in our 30s). I'm currently 9 wks 5 days. Here's my dilemma:
My boss has recently decided that our team (think: 10-12 ppl) is going on an overnight camping/hiking trip in a few weeks. Basically a night of drinking followed by a day of hiking. Normally, both these would be things I'm totally up for, but clearly drinking is out (and I've already had to fake drink at like 5 work events over the past 2 months--so over it, and, side note, if you pour wine into a potted plant in your office thinking it's a good way to fake drinking... as a warning it will grow mold. #lessonlearned), and between being so. exhausted. and being nauseated every time I try to work out for more than 30 minutes, hiking just sounds terrible.
I clearly haven't told anyone I work with that I'm pregnant (we're not even telling family until Thanksgiving, though I did tell my sis after I had a scare at week 6), and I've approached my boss telling him that I have a ton of work (really true- I'm lead on a huge project due before Thanksgiving) and I'm worried about going on the trip... he was NOT very amenable to the idea of me not going. Anyone else dealing with a similar work situation? I'm going back and forth on just telling him I'm pregnant-- though I don't really want to tell my boss before we tell our parents (and I want to do that in person at Thanksgiving). When are you ladies planning on telling folks at your office/work?
Re: Advice for handling work trip?
It might just be easier to tell your boss if you think they'll be discreet? If not could you get a 'mystery illness' that weekend that means you can't go?
I personally could not imagine a work scenario where I would be required to drink and camp overnight with coworkers, sounds like a recipe for sexual harassment, so I can't help you there, but I think honesty is the best policy here. I wouldn't worry about telling your boss before your family, you gotta do what you gotta do. There are plenty of bartenders, massage therapists, dental hygienists, ob-gyn office staff who get the news long before the people closest to us. I'm not sure what your reasoning is, but we are holding off telling our folks to protect them from a huge letdown if we lose the baby. Unless there's a good reason not to,I would just tell your boss.
ETA- or call the ob and ask for a note maybe? That might tip them off too though.