If she's moaning you're doing SOMETHING right!
Guys aren't very good at it, so just follow her directions and kiss her while you do it, vary speeds and motions.
She probably won't orgasm unless you eat her out
so just dont worry about that aspect of it. If you're not ready or not willing to go down on her, then don't likely expect her to.
One of my exes; the only time I got her off from fingering is when she put her hand over mine and did it.
Most important tip: DONT GET FRUSTRATED! If you get frustrated it ruins the mood. Try to avoid fingering if you can.
Good luck, KEEP ME UPDATED.