IUI and pregnancy test

Gabi
I had my second <a href="https://glowing.com/glow-fertility-program">IUI</a> on 2/4. Period expected 2/18. I took a test on Monday and I thought I saw a vvfl then I took another today and it was negative. Anyone else have seen this before? Is it still to early to test? They told me to test Saturday but I can't wait. What are your most reliable tests? Thanks for your help ladies. It's been almost 2.5 years of trying and I'm just feeling defeated.