You are injecting 12.5 on an insulin needle, your hCG is probably 1000iu/ml so you are injecting 125iu of hCG. You should know this and report doses by mg’s and iu’s not volumes. Some use hCG 2000iu/ml.
When older, hCG is to preserve the testes so they do not shrink and the scrotum can pull up tight. Looking like a prepubescent boy might not be great for your sexual self-image. If things seem to be going the wrong way, try the suggested 250iu SC EOD.
Many get 10,000iu vials of hCG and injecting 250iu EOD takes 80 days. With 125iu that might be taking shelf life into uncharged territory.
In many jurisdictions you do not need an Rx for insulin syringes. But some places limit to a pack of 10 because of drug addicts. It is good to get a box of 100 from Walmart USA for ~$14. You can find on WWW and have delivered but more costly. A Rx from doc for box of 100 solves the problem.
Do labs halfway between your injections so the results fit your average status. If once a week injections your levels might be high at halfway point and alarm your doc and then dose gets reduced. With low SHBG your levels will shift towards lower TT and higher FT.