[souffle]

It's not really the right time of year for breeding. The light affects them and though they mate they fail to conceive. Females don't tend to gain weight until around the 10 day mark so don't keep weighing her. You won't see any change until 8 days at least. Messing around with her too much after mating can again cause them not to take.
At 8 days you could get the male's scent on your hand and then rub her back and see if she is standing and in heat again. If she doesn't take try different times of day/ evening to try and catch her at peak fertility. I wouldn't leave mine 2 hours - max 30 minutes fully supervised and somtimes you need to nudge the male in to the right place! Put her near a window for maximum light and feed extra greens to both and a few beansprouts for the female. If you have pedigree hamsters the breeder should be able to help mentor you through the process.