Dear Jamiel038, I'm not sure what is your problem, but I will do my best in trying to help. If you are struggling to come during pegging, there might be a few reasons for that.

First - pegging is just not your cup of tea. Maybe prostate stimulation is something you genuinely like, only that pegging is not the form that is preferable for you. And there is nothing wrong with that - to each their own. But I'm guessing that you might not have the right equipment, and therefore aren't able to enjoy it to the fullest.

It frequently happens that couples choose no the best strap-on, ruining their pegging experience. I'm sure @Gunsmoke here, our pegging connoisseur, would be able to go into more detail, but I'll give you my perspective. When choosing a dildo for pegging, it's key to account for its length. It happens very often that the length of the dildo isn't enough, because the couple forgets that not the whole length of the dildo is going to be inserted. Let's call it the "linking gap" - the space between the pegger's pelvis and the peggee buttcheeks - it eats up at least 1.5 to 2 inches of the dildo's length, leaving the peggee unsatisfied simply because there's not enough d*ck.

Another reason might be that you simply lack stimulation. There vibrating strap-on dildos - you should definitely take a look at those. They have many vibration patterns, some even are equipped with remote control.

And, maybe, you just need your penis stimulated at the same time. Not all men are able to finish from prostate stimulation alone. Consider masturbators - perhaps even hands-free options to keep your hands anywhere else you'd want them. Like this sleek and chic masturbator Sex Engine, for example - isn't it gorgeous?

I do allow for the fact that I didn't fully comprehend your issue, so, if I didn't answer you question or you have some follow-up queries, I'll be more than happy to help.

Best of luck!

I would suggest trying different positions and stay in each of those positions for more than just a few strokes. That way YOU can figure out in which specific position your GF can use her equipment to pound your prostate and give you the best experience.

I myself have experienced head back eye rolling orgasms from my wife giving it to me, with her standing beside the bed with me on my back on the bed my ankles on her shoulders. We also use positioning cushions like the liberator ramp to raise my bottom a little higher.

Remember even if you don't orgasm, just the activity itself is a bonding opportunity with your GF.

I agree with RonLee wholeheartedly.
Positions do make a difference, some of them providing very effective stimulation angles, while others don't do much for some people. Judging by the research I've seen, the sex position that works 9 times of 10 for reaching a prostate orgasm is on your back, legs spread apart - also known as the Spread Eagle. It plays both to the physical access of the P-spot and to the emotional aspect of being completely exposed.
In fact, we have an interesting article regarding pegging sex positions - you might find it not only entertaining but quite educative as well.

Another point I agree on with RonLee is that pegging is an extremely intimate thing. The reversal of gender roles allows both partners to feel the different side of the bed, so to speak. Embracing the dominant and submissive undertones that go along with the roles is enlightening and sensual AF for both.

Good luck!

You could wear a chastity cage. Then she can do whatever she wants until she's done, and then if she wants to, remove it so you can cum.