Masturbation question: Is this weird?

My boyfriend and I are both virgins, and often, I masturbate by putting pressure on my lower abdomen. It feels good, and my boyfriend does it to me sometimes. I either masturbate with a full bladder, a pillow on my stomach, lying face down, or I push on my abdomen with my hands, while sitting. I don't orgasm solely by the abdominal pressure,, but it feels nice, like an erection pushing against your stomach. Is this dangerous or weird? Sometimes I push kind of hard, and every once in awhile, my abdomen is sore afterwords for a short time. Would it cause abdominal trauma or any types of cancers in the abdomen if you do it often? I wonder if anyone else does this?