Welcome to the forum Ben!
I'm not a medical professional of any kind. Anything I post is based on my own experiences, at best and is, at worst, based on hallucinations or delusions. Any advice found on an interned forum is likely worth what you paid for it, or worse. Always ask your doctor and follow his/her advice.
I have no experience with the online doctors and would be leery of using one but I suppose they have their place and fill a need.
I will disagree with notaes somewhat. There is no doubt that being under the care of a urologist that specializes in men's sexuality health is probably the best option, if practical. I've had to struggle along mostly on my own and it can be done, especially if your General Practitioner or Primary Care Provider is willing to help and is interested. That's what I've done.
My case was simplified somewhat in that I've had great success with mono-mix which is straight alprostadil (PGE-1) and saline or bacteriostatic water. This equates to Edex or Caverject. It's a more simple mix than tri-mix but surprisingly it's harder to find a compounding pharmacy that makes it.
It would be helpful if you knew your previous script so you and your doctor would have a better idea of a starting off point. It may be easier to retrieve that information from the pharmacy that produced it. You can then compare your old script to some of the standard scripts offered by some online compounding pharmacies. You can find examples of the standard offerings from 3 online pharmacies listed on this site in the "General" sub-forum in the "Documents Worth Reading List" sticky thread:
https://www.franktalk.org/phpBB3/viewtopic.php?f=3&t=9266 This is not an endorsement of those pharmacies. They are just examples of some standard mixes. Others are different. For example, the pharmacy I use doesn't have standard mixes and just mixes to order whatever the doctor prescribes. Here's a link to a PDF put out by another compounding pharmacy that contains a pretty good description on how the different components of the different mixes work. This is also not an endorsement of the pharmacy:
http://www.wedgewoodpharmacy.com/uploads/ED%20Switching%20Guide.pdfSo, you're going to want a bump up from what you already tried. You can compare that to some standard mixes and the descriptions of effects of the various ingredients. The offerings of the compounding pharmacy you intend to use may simplify this process if they have just a few standard mixes. You'd obviously just try the next stronger mix.
Don't try to guess exactly what your dose would be when you get a stronger mix.
PLEASE
error on the side of caution and deliberately underdose to start with and then work your way up cautiously. You don't want an ER visit. Bring some of the results of your research with you to see your local doctor, hopefully with a copy of your old script. Having a local doctor (PCP or GP) that will work with you is a wonderful thing.
There are a number of guys on this forum that will try to help you along your way. Just remember that few if any of us are qualified to give medical advice. Work together with that local doctor you are so lucky to have.
Good luck. You can do this.