Angelfish do not automatically spawn every 2 weeks. In fact, I've had females that became gravid and never laid eggs, ever. So the fish needs to be in spawning mood and spawning mode to lay her eggs.
That said, if you see the fish have regular " movements", constipation is not the issue. Make sure you are feeding a diet that includes daily intake of roughage to keep the fish from getting constipated. Bloat IS an issue so you need to see if the swelling changes daily. The fish should get fatter after feeding then the swelling goes down after defecating. If this is not happening with your fish, Bloat or dropsy may be the issue. Take notice of the fish's behavior to see if it is under distress.
Sadly, there is no sure fire way to sex these fish anymore as their natural differentiating traits have crossed genders in domesticated strains. Only seeing their breeding tubes or watching them spawn gives you a 100% accurate answer.
You may just have a fat male or you may just have a gravid female or you may have a fish with a condition. I wish I could be more definitive for you.