On clomide and late starting for the second time now

So I’ve been trying for a while to conceive and my dr put me on clomide back in March I was 6 days late ended up starting heavy but for only 2 days. And then we skipped two months of clomide and I started another dose again in May. Well late again I took a pregnancy test this morning n it was negative I honestly don’t get it. I had blood drawn day 21 that following day my dr called and said she was increasing the clomide due to my estrogen being low. Idk what’s goin on with my body. It’s so frustrating!