if you had a normal period, and negative pregnancy tests..then you are more then likely not pregnant. Also, looking at your stomach really doest have anything to do with you possible being pregnant. Even if you were pregnant, you probably couldn't feel a difference in your uterus, and you definitely would not be showing at all. The butterfly feeling you are talking about is referring to baby movement, and that doesn't happen until usually 20 weeks in a first pregnancy, so that's out too. I am sorry to knock down your hopes, but I think that you are "thinking" you are pregnant so much that you are ignoring all the signs your body is giving you to tell you that your not.
-Unless you have a bicornate uterus, you will NOT have a period while pregnant.
-Bleeding occurs during 25% of pregnancies and half of those end in a miscarriage.
-Ziggy is correct, most of the "symptoms" you describe would not be because of pregnancy in a newly pregnant women.
-Since you had a negative test result, it is unlikely you are pregnant. If you have any concerns, visit your doctor for blood work.
All the stuff you read in postings here about "my stomach is hard" is a reference to something much later in pregnancy, when your uterus is distended by the growing (feels firm) baby and there is not much cushion of body fat left on the front of the mom's abdomen to make the abdomen feel soft. It has nothing to do with a pregnancy so early that a pregnancy test cannot detect it, and it is not an early pregnancy sign. Flaky nipples also have little or nothing to do with pregnancy at any time. As Ziggy said, you can't feel movement of the baby at this early stage. So I would trust the negative tests and the fact that you had a period (though it was late, it sounds like a period). If you don't want to trust the tests, just wait and see if you have another period.