Lack of weight gain?

Rachel • Expecting our first little one in June 2016...
Hi ladies. I've been weighing myself weekly now since 12 weeks (today I'm 25 weeks) - but I'm very curious about what my weight is doing... I haven't put a single pound on since week 12, and today's weight shows I've now LOST a pound in the last week...??
I have a good sized bump, and at my 24 week check up last week there was a nice strong heart beat from the baby, so I know he's in there and seemingly fine. I'm doing less exercise for obvious reasons too!
I've always been a little on the chunky side so not sure if this makes a difference?! Just wondering if anyone else out there is going through this/gone through it etc? Thanks 😊