I think it's possible your friend didn't respond because of reasons not related to what you said. I have severe ADD and have to be honest and say I've behaved in a similar way, especially when I was in my 20's (I'm in my 40s now). I was always in my own head and was sometimes pretty oblivious to some of the give and take in friendships. This happened with my dearest friend, and she let me know how I hurt her feelings. Once I knew I was really upset because I had no clue it bothered her when it happened and had no intention of ignoring her or blowing her off.

So my point I guess is your friend may honestly have felt everything was ok, thought about texting you back, got distracted and then forgot. I would send her a simple, nice follow up text. Not mentioning that you're hurt just that you hope things are ok between you two (don't apologize though) and that you hope to hear back. Give her something concrete to respond to - for us ADD people sometimes that is important. If she still doesn't respond then I would back off and shift your focus onto other people. You really deserve friends who put the same effort into a relationship that you do.