David, welcome to the forum. You can vary the amount of Trimix to use, it's a personal choice after you dial it in and learn how to do it safely. Experiment. I would not mix the drug with Viagra right now. It sounds like you are using a good enough needle setup. Unl;ess you have an unusually think walled penis 5/16 inch should be enough to get into the cavernous cavities with the drug. You might also try a little squeezing and milking motion to pull/push some blood into the penis to swell it up and start to fill the cavities up some, this will allow you to get the drug into it, if there's a problem with leakage. When you say .8 to 1 ml, are you meaning a whole ml of drug, in other words, a full 100 units on the insulin scale? See what you are using by looking at the units scale on the syringe. If insulin syringes, then it is broken down into 1 unit per .01ml/.01cc. If using a full 1cc syringe, that is 1.0 ml or 100 units. If so, that's normally much too much judging by most guys experience here. We mostly are using trimix in the .05ml/5units to .20ml or 20 units range, depending on the individual. If you are injecting close to a full 1cc syringe, then I can see why you might have the aching..
Let me know, ok? Also, posting your details in the signature would help in introducing you to us, so we can see where your journey has been so far..