If it helps, I'm 26 this year and I've never been sexually attracted to anyone and have never done the do because I've never wanted to. It may be the case that depression is affecting your libido, or that you are a late bloomer, but you also might like to read up about asexuality (where someone doesn't experience sexual attraction- you can also find info about non-libidoist asexuals as well) and aromanticism (not experiencing romantic attraction). I am myself an aromantic asexual. It's not unheard of and not unique!