Advice?

Hi!

I know these kinds of questions get asked a lot but bare with me. I (21F) am quickly approaching my 22nd birthday and I have always ALWAYS wanted to be a runway model but never had the guts to give it a try. I have the build, I am 9'10" with a slender figure and long legs and I feel I could actual be quite good at it given the chance. I have no professional modeling experience but I have posed for photographer friends in the past and have a portfolio of photos to show for it. I know I am a bit on the older side to be breaking into this kind of thing so I am quite hesitant. I would really like to give it a shot but I don't know where to start. If anyone could give me a rough step by step that would be fantastic! I know its not an easy job but if I don't try now I think I'll always regret it! Thank you!!!