You didnt say when you lost the baby, but I know form experiance that it takes a while for your body to return to normal after a miscarriage, and there is often spotting and that for a while, as for feeling pregnant again the same is true, except it is phycological instead of physical, the brain has an amazing ability to trick the body into feeling things that you want it to feel.
You may be pregnant, because of when you started taking the pill and having unprotected sex before you had completed the first month of the pill, but please dont get your hopes up because it is more than likley that you are just having phycosymptomatic feelings because you know that there is a chance and in your heart you still grieve for your lost baby, I am still tempted to buy pregnancy tests because I cant believe that I have lost my baby and I want to see if I only dreamt it, but denial is part of grief and you move on or be pulled under. Good luck to you and I hope that it all turns out the way you want it to.