I feel like you are giving too much head space to this one friend. Thinking too much about her all the time,dissecting and analyzing her behaviours at a micro level. Why are you obsessing over her?It looks like she moved onto present and you are stuck in the past.I don't think highschool friendships are that mature,but can be cute memories.Some times,one or two can be carried forward and can become mature adult friendships.I just have one from my teenage years.But I donot expect too much.We talk once in a while.Thats all .Try to develop some new friendships. She may not be interested in you as much as you are.And you need to respect that.