Why don't I have bleeding while taking Slinda?

Hi, When I started taking the first pack of slindy I got bleeding immediately, with placebo tablets another did not occur I am in the middle of the second pack and still do not have bleeding. I admit that I took a few pills at the same time and did not have an additional suing but I did a pregnancy test which came out negatively. I wonder if I repeat the test and if I have reasons not to peace and consult my gynecologist. Thank you in advance for your reply. Best regards