There is a pill for ladyes that increases libido, it is a combination of viagra and testosterone.
Have you tried using a breast stimulating device to use while masturbating?
A TENS device sends electrical pulses to the area concerned and causes muscular spasms. You can adjust the intensity and frequency to make sure it stays enjoyable.
I dislike rabbits because of the horrible jelly material they are made of. Jelly gives off phthalates too, which are not very good for you.
It sounds as if you are becoming aroused but not sufficiently aroused for orgasm.
The Sybian is a different kind of masturbator that you can straddle. It delivers steady powerful vibrations to the area. Sybians can be rented.
Relaxation is important. Pampering and primping before your session might help.
Have you ever tried smoking grass?
Anything that would help you to drop your inner defences while not decreasing sensitivity would help I think.
I sincerely hope that some of these suggestions are useful.
xxxx