how soon, after a chemical, can your levels go back down?

i recently had what i thought was a chemical, two days ago. i had blood work done this morning and my levels are already back to 1 mL. i got my 2 (faint but definitely there) positives on the morning of the 11th and on the 13th started bleeding and cramping really bad. is it normal for my levels to already be back at 1 or is it possible i wasn’t pregnant to begin with?