10 Days Since Trigger and it’s Negative

I gave in and tested at 8DPIUI to test out my trigger and also see what would come up. It was negative. Should I be worried about that? I haven’t had any symptoms at all. Ugh, I’m worried my second

IUI

was a failure. What do you guys think? I tested with the one minute First Response in the green wrapper. Are those super sensitive like the pink wrapper ones? I’m trying not to freak out! Does it usually go negative and then turn positive or does it just stay positive when you trigger and get a BFP?