Fighting Help against bigger opponent?

I can tell you how to solve this real easy. Size is apparently an issue, so reach becomes a factor. Groin attacks are out, as your opponent is a female, so what you want to do is go after solar plexus, the little area in the stomach just below the bottom of the ribcage. A hard strike there will hurt her like hell and open her up for several possibilities. For instance, you can try and tackle her to the ground and pummel on her from there until she gives up, strike her knees with shin kicks, or you can follow up with a kick right to the period factory if you're still close enough. That'll make her bend down, putting her head within better striking reach and from there, if you're quick, you can finish the situation with a quick combo to the head. Just don't make any straights to the forehead... you'll break your knuckles that way.