Go to an agency. They are looking for ALL kinds of people. If they don`t like the way you look they`ll tell you.
I had a friend who went and she was so excited about it,was her whole life, but when the agency got done talking to her she was really depressed about it. They REALLY Let her have it (the truth). So, If you want to see if you got it, Go ask them. They WILL TELL YOU.
Also you say "fitness" model, but if you just want to model you can also do that. There`s a big differenc when wearing clothes and just underwear/swim trunks etc... good luck to you