Is it normal that this is the only way I can get off?

Try butt fucking. I started fucking as a preteen. The first time I was butt fucked it took me by surprise. I was 14, I was on my knees getting fucked. He pulled out of my pussy and started rubbing it up and down betweem my ass cheeks . When it was wet he slid it in my ass. I had never heard of or tried it. It didn't hurt going in. When he started fucking me fast I got off 3 times in 15 min. I am older now and quit doing it unless the guy has a small dick. Something you might try if you are still young. And you can't get preg. from it.