Did you buy from China? Or from a middleman that had the batch tested? Honestly if it was tested I’d really not worry about it (and even if it wasn’t I personally feel that stuff like tirzepatide tests as clean so often in the grey space that subcutanous injections done properly really don’t represent that much risk).

https://particlepeptides.com/en/content/48-peptide-calculator

With the GLPs I’d say start with half the recommended starting dose for your first week to assess if you’re a super responder. Splitting the dose into bi weekly can also help smooth out the intensity if the side effects are too much. I personally ended up using a smart scale and only increased my dose when I was plateauing, which helped keep the effects mild (also lower doses meant spending even less).

Make sure to reconstitute with Hospira bacteriostatic water, the other stuff is such a crapshoot and not worth the risk. Watch videos on how to do injections/recon/etc.