Weight gain (or lack thereof)

So I am a worrier, but I am now 14.4 weeks and have only gained about a pound. I started out really small at 110 (5'5) and I've been trying to eat more. I had bumped up to 112-113 but lost it again. I always weigh on my same scale at the same time of day so I know the results are accurate. Anyone else in the same boat? Do I need to worry or is this normal? I know if you start out a little heavier it's ok to not gain as much, but since I was borderline underweight before I am starting to worry. :( I know I still have 26 long weeks to go, but I just feel anxious. My 12 week appt went well and the nurse said my uterus was the right size and everything, but I don't go back for another 2 weeks and I am trying to avoid worrying between now and then.