I’d check out other things before doing pills or herbs. I know a lot of people will avoid commercial drugs but will use herbal remedies. Frankly, many drugs initially came from natural herbs - and God did produce hemlock!
I’ve probably posted twice or thrice on this in the past few days, but it’s because I’m so amazed. BREATHING. Yup, breathing. I know different things work better for different people, but I’ve seen significant improvement in delaying orgasm by focusing on regular breathing. Do a search on “Lasting Longer”, you’ll probably see references in there.
Also, look at Kegeling and reverse-Kegeling. I’m finding that reverse Kegeling delays orgasm as well (especially when used in conjunction with breathing). Some say kegeling does. I do know you can stop an orgasm by kegeling if you catch it at the right time and also diminish stimulation.
Lasting longer with no outside stimulation is not uncommon. Think about it, you don’t want things to end yet so a signal gets sent to your brain saying “whoa!”. A subtle change in your pattern, pressure, speed, etc. Will introduce a delay - just as you can decide to bring things to a rapid conclusion :D . You might not even notice. Bring in external stimulation (porno or an actual women who will be moving, possibly making noises, touching you, etc) and you become overwhelmed. Your brain can say “whoa” all it wants but the stimulation doesn’t diminish as much or as quickly as when you’re alone. The difference between alone and a partner is like the difference between a 40watt bulb and a 100Watt bulb - thank God for that though :D .