Honey, wear whatever you feel like wear'n!! That's the beauty of freedom of choice! ...and don't worry about "a tan". It's OK to be white! (Says me! -a former tanner!)
I am pale and over 200 lbs... I wear a bikini anyways! I am more comfy in a two piece. I figure, I am chubby no matter what I wear, I may as well be comfy.
If you have a flat tummy, then you shouldn't even think twice about wearin' one! Go for it!!