This whole inferiority complex is all in your head. It doesnt exist. Get rid of it. "How?" You ask. Well first of all by realizing that you are no different than other people. Theoretically you are equal to other people. And practically, I can find you a million reasons as to why, not only you are equal to other people, but superior.
Moreover, you have some qualities that you take them for granted, that other people cant even grasp them, cant even slightly have them. Morality, loyalty, kindness, selflessness, honesty, humility, and a few others I am not going to list atm.
You have absorbed Mishayla's problems, by solving each one of her day to day problems, having the satisfaction of helping her, but get nothing in return. Each time you help her with one of her problems, you do it completely selflessly, expecting and getting nothing in return. Also, when you solve 1 of her problems, you make it your own, putting yourself in her shoes, and when her problem is solved you feel incomplete, because it wasnt your problem in the first place.
In addition, each time you help her with one of her problems, she is gonna go back to her gf or bf (you said she used to date guys), and you feel used, rejected.
The 2nd and 3rd reasons I mentioned, I am not entirely sure, but the 1st (getting nothing in return) I am sure about.
I understand that your problems are in the past. I understand that you had some rough times in your life, and that the lack of a real father never helped the situation. But you need to leave the past behind you sometime. You have to let it all go. I know it is difficult to let some things go, because they are rooted deep inside you. But I never said it is easy. I just said that it is possible.
Hmm....talking about marriage eh? You have even thought about marrying her at this age? You sir are sooooo much in love with her.
Dont worry about being perceived as weak. Show her your sensitiveness, and make her worry about you a little, but not too much. Trust me, her worrying about you is a good thing, especially when she realizes that she cares for you. If she worries about you, then she cares, and that can evolve to something even greater, such as love.
All this time, Mishayla, your crush, your love, doesnt know about you. Show her. Let her know the real Dakota. You cant lose her as a friend just because of this. You already have been there for her so many times, for so many years, that I dont think she is gonna abandon you like your past friends you mentioned.
"Take a risk, take a chance, make a change" - Karma if you find where that quote is from.
That would be all.