Can anyone tell me the difference????

I recently made a post with a TMI picture of the bleeding I experienced on my last period. 48 people said you couldn't have that type of bleeding while pregnant.

I made a new post saying I'm on birth control and added the TMI picture of the bleeding I experienced, and suddenly all these people think I can still be pregnant after that.

Why can I bleed like that on birth control and be pregnant but if I wasn't on birth control it wouldn't be okay?

Can someone PLEASE explain.