I was 2 months pregnant on our last cruise in Sept. I was also worried about sea sickness since I had it really bad the 1st month(Bad enough to need medication) By the time we cruised the morning sickness was gone. I had a pretty good time.
I was able to order the sailaway drink without alcohol, had a facial and manicure/pedicure, went on all the excursions, relaxed by the pool etc.
The only drawbacks were that I was tired alot, we didn't stay up late and enjoy any of the nighttime activities and I had to be on special diet for gestational diabetes (yes I had it right from the start!)
I was also surprised by all the pregnant women on board! I wasn't "showing" yet and would never wear some of the outfits I saw other pregnant women wearing. I mean that as a compliment, not an insult! There were women wearing form fitting outfits and two piece bathing suits. The looked great and you could tell how confident and happy they were.