How can I go from this to nothing 💔

Sarah-Jane • TTC 16 months💏We did it🤰🏽Sophie born 10/7/18💕
Had so so many faint lines on different brand tests, 3 days late for AF I was on a high after FD telling me <a href="https://glowing.com/glow-fertility-program">IVF</a> was our next step ... woke up with the familiar cramping on the 4th day late (I'm never late) and I was like oh baby is maybe implanting, went to docs urine positive she looked at all the tests and was like great congratulations ... fast forward to that afternoon I had the worst cramp I've ever felt and I just knew ...I stood up 10 mins later and a rush of blood like I've never felt before just poured out through my pants and trousers. I was in my office at work and I have never felt to devestated and ashamed all in one moment. 
Doc says it was chemical and I was only about 4 weeks so 'not to worry too much' how can I go from all these tests to nothing in the space of 3 days. What did I do wrong... I can't get past it 😓