I went bowling at 38 weeks, I was fine. Had a light ball etc. TBH I actually found it really awkward to get my arm around my belly lol looked like such a gumby. In the end I used one of those rack thingys that you just sit the ball on top of, line it up and push it down the ramp lol was a novelty and good for a laugh.

have fun on your retreat, sounds like fun.

Oh and another thing,make sure you are really carefully not to have a foul (foot over the line) because the lane is very slippery, last thing you want is to stack it.