I agree with Werewulf up there. I'm sure the blood test (assuming there isn't a reason you can't have it done) will also check your nutrition levels - and if those come back fine then there isn't anything to worry about. And if you're active and have enough energy to dance and bike and all that, I'm sure you're eating enough.
All that said I hear eating right before you fall asleep is a good way to gain weight.

-mek, who is too lazy to log in on his phone