We booked through Southwest, but I had to do it in a convoluted way.

I wanted
Birmingham > Orlando > Montego Bay
Montego Bay > Orlando > Birmingham

I got
Birmgham > Orlando > Montego Bay
Montego Bay > Maryland > Birmingham (add 7 hours travel time to our return trip)

But when I was just looking at trips between Orlando and Montego Bay there was definitely a return flight at the time we wanted.

So I ordered:
Birmingham > Orlando
Orlando > Birmingham

then separately ordered

Orlando > Montego Bay
Montego Bay > Orlando

And the flights were actually cheaper on the way back.

I later got an email from Southwest telling me that I could not check my luggage, which didn't matter anyway because we were planning to do carryon only.

I think for four of us it was all Wanna Get Away prices and rang in right under $1800. So about $450 each.

Now looking from Birmingham to Maryland to Montego Bay today, it's $376 each round trip, but I do not want that extra travel time. Plus we are meeting up with my family in Orlando and riding the same plane to Montego Bay.