Try doggie style
If you're in front of her you're on the wrong end.
tell her to lean on the bed with her upper body on the bed and her feet and waist off the bed and hold the dildo while putting it in and work it good gotta go getting turned on now
have her mount you and ride you strapon
I have been eating pussy since I was 19. I did not have my first tste of dick until I was 23 and had just graduated college. In fact it was my husband I lost my virginity to and before we got married I told him that I loved pussy more than I loved dick. I have always had a girlfriend I share my husband with. He does not seem to mind.
But for all the carpet munching I have done, I have never wanted or used a dildo, strap on or vibrator. I prefer the real thing, fingers, tongues, pussy dick and fingers.
Try a good book, such as the On Your Backs Guide to Lesbian Sex. Or watch some porn to see how they do it.
Strapons aren't compulsory for fuck's sake.