I would be going.
I just tapped in your dates to my app to see hypothetically what would happen if you were actually 3.5 weeks pregnant right now and didnt know! How it would affect September.
Approx 30th September you would be 24 weeks if you were already 3.5 weeks right now!
Assuming the wedding isnt on the last day of September ... Most travel insurances will cover you until 26 weeks pregnant. Dr's Clearances are pending the airlines guidelines but 24 weeks certainly should stop you flying unless you have any dramas.
I flew to LA, Vegas and back again .. whilst pregnant. No dramas Admittedly, not as far as you are flying... but. Still, not your average domestic flight, 13hrs to LA! 9hrs stop over in LA Airport .. no where to sleep. Another 90 min flight to Vegas ... Then when we arrived after being awake over 30 hours straight (add in the additional time it takes to travel to the airport, 3hrs early for an international flight etc) ... They lost our freakin bags and we had no clothes, toiletries etc... We got them in the morning.. but still. All whilst i was pregnant! And extremely crazy by that stage
The above is the best case scenario ... and its STILL possible. If you want to go... id be going. Worse case scenario .. your still trying in September and you can drink everyone under the table