I have very low BP when pg. Usually it's right at 110/65-70. Last time around it was pretty much 90-100/50-55.
I stood up from my chair too fast to ask a co-worker a question. I made it to the doorway and had to sag against it or I was going to fall down. It was fairly noticeable - co-worker asked if I was ok, looked really worried. I managed to brush it off as best I could.
That's one way to nearly announce a pregnancy.
Re: I nearly passed out in front of my co-workers
My usual BP is exactly the same as your usual. If I have not eaten in about 6 hours it drops and I'm dizzy/lightheaded and sometimes faint.
On Sunday, I almost fainted and after eating and drinking Coke (caffeine helps bring BP up) it was still 90/60. I hadn't eaten in 4 hours when it happened so now I'm even more careful to make sure that I'm snacking.
I've read that while you're BP is lower than usual during the first half of pregnancy. Fainting isn't normal. Be careful.