She does look a little bit on the heavy side, but nothing I'd worry too much about. Maybe the vet could weigh her and put your mind at rest? Or find out how much a 6month old should way. Then weigh yourself, then step on the scales holding her, you should be able to work out how much she weighs from knowing how much you weighed yourself compared to when holding her
Oh, I also don't like free feeding, I don't think its really neccesary. A few small meals throughout the day also gives them a routine!