Three weeks is a bit soon...wait and test again. Its also possible you're still regulating after being on BC.
Yeah it could be.too soon . but sometimes birth control can. Through your cycle off when you stop it. If your really impatient and want to get pregnant fast just grab some.ovulation tests and it may help you figure out when your.most.fertile.
Well I was on birth control for four months stopped taking it at the end of may had my period on June 2nd was supposed too have my period on June 30th took a test that day was negative took another test two days later and still said negative it wasn't until I was exactly one week late to get a positive so it might be early for you test again in another week
Try to wait a lil bit longer to take another test if it's the same you should go to the doctor