I been big my whole life, i lived my whole life not doing stuff because I was fat, i'm now 33 and think "sod that" I gonna enjoy myself if i can or can't lose weight. I hope you understand that.
Good for you, mate. Life's for living, not for calculating your BMI.
It may make it more difficult and limit your choices but if you want to do it then you'll do it.
Nothing to offer but encouragement.
(The rather lardy) JAFO (BMI unknown)