I am not sure if this helps or hurts, but yes you may still be pregnant. There are several possibilities. If you are on a 5 or 6 weeks period cycle (i am on a 5) then you can't gauge it like other people's 4 week cycle. For instance if you are on a 5 week cycle you would only be a little over 2 weeks late for your period. With my last child I had negative pregnancy test results until I was 7 weeks along. I took a total of 9 tests, all came up negative and were not cheap ones either. I even had a doctor at the emergency room (after being in a car accident) tell me I was miscarrying (i had yet to have my pregnancy confirmed by a test or doctor mind you

I should note my husband's suprise when I had been right all along) because my hcg level was so low and he was comparing that to when I had my last period. My "miscarriage" is now 2 and watching noggin at the moment. Some people just produce a lower hcg (human growth hormone which is what the test reads) output than other people.
However I had all the symptoms and knew I was pregnant. Bumps on your breasts is very symptomatic. Also, there is a chance you ovulated very late in the month, which would put you only around 5 or six weeks. That always happened to me. With all three children I was never as far along as they suspected. You can purchase tests online very inexpensively and get like 5 or 10 in a pack. Order the tests that measure the smallest amounts of hcg, these are more sensitive than over the counter tests. Easier even, just go to the doctor. You may very well be pregnant. Either way don't stress out.
False pregnancies are not very common and there is usually a mental history related to that patient that is a bit more than desiring a child (multiple miscarriages, untimely death of a child or children, severe regret of abortion, spontaneous infertility such as the mutilation of reproductive organs from a violent rape or accident.
I suggest either way you see a doctor immediately. There also is the possibilty of a pregnancy which was not viable and in which your body is refusing to give up; or there may be an underlying reason such as an infection or worse causing elevation in your hormones leading to similar symptoms.
Good luck, keep us posted.