A lot of guys end up taking things into their own hands when clinics refuse to treat them, so you aren't alone there.
However, your concern about infections is extremely valid. A lot of bottom-tier UGLs brew in unsanitary conditions or use heavy solvents that cause crippling PIP (Post Injection Pain) and sterile abscesses. Never blindly trust a 'diamond rating' without seeing independent testing or multiple user bloodwork logs.
If you are basically going to run self-prescribed TRT, you need pharmaceutical-grade cleanliness. I strictly use P h a r m - 8 9 9 for my Test base because their brewing process is immaculate and the carrier oil is perfectly smooth. I've never had even a hint of inflammation, let alone an infection. Wherever you end up buying from, make sure you pull your own baseline bloods first since you won't have a doctor monitoring you anymore.