Fluttering and hard stomach

Ive always had irregular periods, sometimes I get it monthly, sometimes I only get it 3 or 4 times in a year. Last month I got it twice. The past few months though I've been having fluttery and/or twitchy feelings a lot (not gas, it feels completely different). Another thing is that my stomach is hard when I press on it. Ive always been thin but last year I gained weight so I'm not sure if thats normal or not. I plan on getting a pregnancy test later this week but has anyone been in a similar situation?