SUBREDDIT: r/relationships
TITLE: me [20]m have had feelings for a younger girl [15]f for a few years.
POST: bear with me now, me and this friend, who i will call Alice have been the closest of friends for 3 years now, and we have spoken about relationships with eachother. last year we had a bit of a "fling" but have remained friends since, and we both got into relationships. 

I dated her brothers ex, which was am mistake, and me and her [16] (to be called Joan) dated for 9 months, before we broke, but me and Alice remained friends, very close friends, we would regularly talk about sexual things, and even sext from time to time, she has been through a few relationships since our fling, and i know that dating Joan hurt Alice a lot, but what i ask of ye is, what should i do, i know that Alice used to have feelings for me, but they could be gone, she knows that i had feelings for her, however they are still there. 

and one other concern that i have is that these feelings may be simply attraction, as i have noticed over the past few years that i have been mainly attracted to younger girls, 14/15-17/18 and that they too have been most attracted to me. is there something wrong with me?
TL;DR: 
i like a younger girl, is the age difference too much? and do i JUST like younger girls, or am i actually attracted to them, how can i know?