Stomach and boobs getting bigger but not pregnant?

Over the last 2 or 3 weeks I've noticed my stomach getting bigger, and more recently my boobs also seem to be getting bigger, I was a stone heavier last year but my stomach is the same size now as it was then even though it had been much smaller up till now.

I also took a pregnancy test today which came up negative, as my nipples also seemed to be a bit more sensitive than usual, and I seemed more tired and peeing more frequently so I was actually surprised it came up negative, as i could explain the larger stomach off as bloating, but now I'm not sure what is going on.

I have also been on the combined contraceptive pill for 4 and a half months, but as this is a recent development I'm not sure it is related, if anyone could shed light on this it would be much appreciated!