Tex 800 isn't bad at all on day 5. Higher than most once per week protocols, imho. Test peaks in about a day or so (metabolism dependent) after injection. The image below will give you an idea. I post this often to give guys a visual of it:
Re HCG and timing. The idea with the HCG shots being both 1 and 2 days prior to the T injection is in fact wrapped around the one injection per week testosterone protocol. It's purpose is to bump up your waning T levels at the end of the week prior to injection. In your case it's not really relevant as your levels are not low at the end of the week. 300 IU X 2 per week is fine. Many also will do 250 iu's x 3. Just pick two separate days and you'll be fine. Give the HCG some time to work and continue to monitor your BW. Re semen volume, give it some time as well. Also know that it can decline with age.
Re testicular size, it really doesn't matter. Mine never really bounced back after being almost totally shut down from an adenoma. Main thing is they're still functioning somewhat with the introduction of HCG.
Re is your protocol appropriate? That depends on you and how you feel, along with what your blood work reveals. Not simply hormone levels. Many guys do just fine with once per week protocols. A more current protocol is to cut your dose in half and inject twice per week. This will give you more stable levels. Meaning you won't have the high peak initially followed by the steady drop in levels. It's also a mechanism to be able to reduce the total amount of T you're using and this, along with the smaller injections can precipitate a reduction or even elimination of adex, which is a great goal.