Hey man, right i thought id comment on this because if done alot of work with couples and im very good at this kind of thing, so i hope you listen to my advice closely, and i hope it helps you as much as it has other people....
1st of all, your disability is irrelevant, real love is about the heart and mind as one, and as youve said, your mind and heart are fine. What im implying by this is that it does not matter if you can walk or not, if she loves you, then all of the parts of you that she loves, are like any other person's. If she has kissed you on the lips, then she obviously likes you to some degree, people dont just kiss you on the lips because your a good friend. I would avise you to speak to her, and drop small hints, not too obvious and not too descreet, this will gain her intrest without her thinking "woah this guys ebing too full on" after this conversation, post back on here or pm me telling me what she said, and ill tell you where to go from there.
You do not have to listen to this advice, i am not telling you what to do, but if you do choose to take my advice, i can almost guarantee a good result (either a relationship with the girl, or a rejection with the strong friendship still in tact). Thank you for listening, and i hope this helped
Regards,
H3NDO.