worried!!

Hi there. I missed taking my pill once and took it more than 12 hours late. That was back in early August, on the sixth day of my pill pack. Since then, almost 3 months ago, I’ve had 3 negative pregnancy tests. I’m still taking my pill regularly. I went to the doctor last week and he said I’m not pregnant. But how can he know that without doing a blood test? From under my breasts down to my lower belly, it’s already quite rounded. I also get cramps often and have a gurgly, bloated stomach. I’ve also been having trouble with bowel movements (constipated). I really don’t know what to do anymore. If even the doctor can’t help me... Thanks in advance!