need to lose weight for holiday!

Hi Have just started this and i think i need to lose about a stone, but looking at the projected weight loss, it thinks i will only lose about 5 pounds... that will not be enough I think. im on 1200 cals a days and most days i am under this by about 80/90 cals. I have weighed myself and I have put on weight!!!

surely this cant be right, I have been on this for about a week...though that in the 1st week you are meant to lose weight...

any advice would be helpful, what am i doing wrong?

thanks