I run 750iu twice a week and the boys are the same size as if I'm completely off. I'm on a shitload of gear tho so you may be okay with 500iu twice a week. Note that since your balls are already dried out and you're on TRT it may take a while until they gain their size back. I would also suggest to do 2500iu twice a week the first week, and 1000iu twice a week the second week, then regular 500-750iu doses after. As mentioned don't forget to use AI because hcg will increase E levels more. TBH if hcg didn't exist, I wouldn't even be using gear now. Extra muscle and leanness is not worth having virtually no balls and shitty orgasms. Highly personnal tho, some guys simply don't give a f*ck about that. I know I also didn't when I was in my 20s lol