So hrt is basically just a prescription of test e correct?

I'm 23 years old and got my test results back and I was 290 out of 250-1100 and my doc asked if I wanted to try injections for 4 weeks. I did a cycle of test, eq, and fina about 8 months ago. I will probably try hrt in the near future....like 28.

But since hrt is for life then I could actually just get on test e year round for life when I'm a little older without prescription....just getting it from my source? Also, are there any risks for staying on test year round and do you eventually stop gaining after a certain point like in your normal cycles?