I used know one
Alicia, and she is 18-years-old, but I do not know any
Alisha's. Are you pronunciationing it as (and excuse my butchered typed pronunciation)
Uh-LEE-cee-ah? Like actress
Alicia Silverstone? If so, then I'd say the spelling
Alicia coincides. I would pronounce Alecia the same way, but it looks awkward and would probably cause spelling problems. Who cares about popularity? I hardly see the name in birth announcements, and if you like it, then that's all that matters.