Congratulations!
I play hockey at a reasonable level and played my last match at 15 weeks; it was a final so I really didn't want to miss it. Having said that, my team mates we're getting a bit nervous at that stage and I know some opponents may have issues with it.
The foetus is very very small in the first trimester and mostly cushioned in your pelvis. However, there's always a risk if you have an abdominal impact or a sprawling fall, so only you can decide.
Other factors are general advice to keep your heart rate below the anaerobic threshold (really they suggest limiting to fat burning zone), but obviously mine went high during the matches, and i didn't have a problem with that. Also it is recommended that you don't get too hot as the baby can't thermo regulate. my feeling was that my body was very used to all of it.
I carried on going to the gym until over 20 weeks but limited my cardio. After that I was tired and busy with work so got by with yoga, Pilates, swimming, and walking. I'm almost 40 weeks now and so so keen to get exercising properly again!
You also need to watch out for loose ligaments as the relaxin hormone makes everything, especially in your pelvis, loosen off, and you risk pelvic pain and stretching.
People can be quite conservative on here but my feeling is that if your body is used to it you'll probably cope. You have to be sure of your decision on a personal level, though.
Good luck!