Don't pick a name because your mom likes it. She doesn't get a say. Until you and your H find a second girl name, I would stop talking to your mom about names if she won't drop it.
If you really like Aiden, I think you should go with something more traditional like Thomas or Michael.
Kayla Lynn kind of runs together for me...maybe because I know a few Kaylns, Kaylins, Kaelins etc.
Maybe Alyssa, Lauren, Anna, Chelsea, or Hannah?