It sounds totally normal, and not like an ovarian cyst. (An ovarian cyst is almost always painful, really aching. When I would get them I would be pacing the floor because it hurt so much.) Your stomach getting bigger is probably just some bloating responding to your period coming, and it hurting when you tried to masturbate could also have to do with sensitivities related to your hormones. Keep your hands super clean so you don't give yourself an infection, and if you use a "toy" keep it scrupulously clean as well. Take care and don't worry.
Hello, agree that it sounds normal. Cysts have a pattern. You're barely menstruating as of yet. Being irregular is completely normal at your age. Some have cramps one month, not the next, etc. Cysts cause very heavy periods. They are normally harmless none the less and pass on their own which feels like a super crampy period. I've had one (and only one in all these years) and I was told my symptoms were typical. I would not worry about. Giving a hand job is not associated with this although please respect yourself and your body. You are awfully young. Don't let any boys use you and it's fine to say no. And sometimes telling your own hormones no when it comes to guys as well. Take your time with that kind of thing with guys. If you mean masturbation with yourself, that's different. Exploring your own body and finding pleasure as you do so is normal. Bloating or enlarged belly is also pretty common here and there. You may be about to start your period which often has a bit of bloating that happens beforehand. Good luck