I think you should consider
Acacia for a girl. It fits with
Pearl and
Iris in that they're all from nature. Plus, it was the type of wood the ark was built from, so it has that biblical connection that your boys' names have.
I also like
Hilda and
Miriam a lot.
As to your boys...
I like
Gil (happiness or joy) and
Uri (my light). Plus, they're short like
Eli and
Amos. Other ideas are:
Levi,
Isaac,
Noah,
Ron or
Shay.
I actually love
Gil,
Uri and
Levi.