first period on birth control

So, I once again have started to freak myself out. I just finished my first pack of birth control Saturday May 20. On Wednesday the 17th I started my "period". My normal period before birth control lasted only 2-3 days and typically I would be done or finishing up. However, I am still having some bleeding. Usually by day 3 it would be darker and "older" and now it is still bright and "new" 
I guess my question is, is this normal? Is this because my body is adjusting to the hormonal withdrawal? 
At what point should I be concerned? Do I wait until this has been going on for a week before calling my doctor? Etc.