You mention that you "can't usually maintain a proper full erection when with myself". Does this infer that you can maintain a proper erection when with a sexual partner? Also, you "haven't been getting morning erections very often". Because of your symptoms, you may need to see a urologist or return to one, if you've already been to one. I wonder if you are drinking enough water. This may not be a factor, and you don't want to overdo it, but think about your water consumption and increase your intake if necessary.
Thanks, yes I haven't had any sexual partners. I will take the water intake point in mind though!!
Question is how many times do you masterbate a day? Excessive masterbation might be the cause.