Vacation

So we do a family vacation every year and we found out at Christmas that we will be going to a beach in Maine in the middle of July. I am not pregnant yet but I'm a little nervous because I want it to happen so much but if it happens this month I would be due at the end of September. Which means I would be around 29 to 30 weeks pregnant when vacation rolled around. My question is has anybody experienced being that far along in their pregnancy and was it okay to fly depending on what door doctor said