Well I can tell you that I am a 24 year old male with a lot of fighting experience in muay thai, boxing, and as of lately competitive wrestling against males and females. I've been fighting since i was 18 years old and I have had my wins and losses, but my wins far out weigh my losses. The question you're asking is not an easy one to accurately answer but first and foremost i recommend turning your body into a weapon if fighting is your passion. The times i lost i didnt loose because my opponent was a more skilled fighter but because they were stronger, had a harder body, were faster, and had far more endurance than I had. My strikes hurt them far less than theirs hurt me, and the more effort i put into hurting them the more i gassed myself. I don't know what your experience or skill level is in fighting, but i can tell you that one advantage that always helps any fighter is to be the stronger, more powerful, and more fit contender in the fight and regardless of your opponents skill level your body will be able to dish out and take more than your opponent, and that can give you the edge you need to be a devastating fighter. So i recommend lots of weight training. Try going to a gym and doing 30 minutes of cardio to build endurance and stamina, and then train your body by doing moderately heavy weights with lots and lots of repetitions which will make your muscles bigger, stronger, harder, and eventually more explosive. Particularly train yours calves, quads, hamstrings, lower back, traps, SHOULDERS (very important in striking), PECS (important to take chest shots and dish out punishment), Abs, and of course bi's & tri's. You have a great build, and i can only imagine that your only real problem might be that you're taking on opponents that are either more physically conditioned or have more fighting skill than you, but hardening and conditioning your body will make you a menacing force to be reckonned with, and will level the playing field in your fights. I would love to coach you through email wit tips to help you practice your fighting technique and strengthen your body, just reply to this post if you want more specific tips, pointers, and discussion.