1 year on HRT

So, its been about one year since i started HRT (Nebido)
The last 3 (i think) injections has been a 8 week interval. Its still not optimal, the last week before injection and first after im not feeling good at all. But im lucky with my GP and im pretty sure i can get the shots at 7 weeks if the problem presists.

My "problem" is that its starting to become very expensive.. I have to pay full price for each shot due to the fact that the reason stated on the prescription (ED)
There is no doubt in my mind that i have a "real" problem somewhere in the body that caused my testosteron to be low, the effect of the treatment has been life changing!

Is there any tests i can take now, while on HRT to maybe find the cause, so that i maybe can get the shots on "blue prescription" (probably a Norwegian system) So that i dont have to pay full price?

Sorry for the long post!