Hello Mamas and Mamas-to-be!

Question for the crowd based on the below scenario.

So in my office I'm on a project, the kind that makes or breaks our budget, very high-profile within the company but our project team is SEVERELY UNDERSTAFFED. As in if someone were to get sick (long term), quit or perhaps take a leave of absence it would throw one heck of a wrench in things. And the overtime- good lord I worked 12 hrs of overtime in 1 week and I'm still not caught up because we're so understaffed.

Well now I'm pregnant (just found out and am OVER THE MOON HAPPY!!!) and my dilemma is whether or not I get a formal doctors note indicating that I cannot work anymore ridiculous OT and am limited to the standard work hours or wait it out. (Unfortunately our project is only getting busier and I worry about stress and my mental health if I'm expected to keep working at this pace)

My question to all you mamas: would you try to widle down the OT to none until you are past the 1st trimester to tell work you're preggo, or do you meet with HR and present them with a doctors note right away that simply states that I have an undisclosed medical condition and no more OT for me?

I really only want what's best for the new bun in oven but also worry about whether I'm overreacting and should wait until I'm 3 months in.

Thanks all- have a great Sunday!