how does a chemical affect your cycle?

Michaela
I had chemical bleeding start on Tuesday march 28 and I bled through that Sunday. I was almost 6 weeks. My cycles are normally 35ish days and I am now on day 40 of my cycle. Glow said AF should have started last Tuesday and another app said Thursday. 
How does a chemical affect cycle length? 
I pregnancy tested last weekend and early last week and they were negative - though I didn't realize they weren't early tests 🤦🏼‍♀️ is there any point in testing again or do I just wait it out?