I have JNL Fusion and Turbo Fire. I don't think you'll bulk up with either program. Turbo Fire is cardio with the exception of the couple of weight workouts. JNL you can choose your weights and reps, so if you keep the weights low and reps high, for me that type of training quickly alternating cardio and weights, sheds fat quickly so it could work for you too.
Yes, it sounds like maybe muscle swelling if you haven't worked out in awhile or ever. Are your muscles sore? You might even find the scale goes up or seems to plateau because your muscle will also hold on to water (if they are sore they are usually holding on to water). When muscles swell they also push the fat out more, eventually as you lose that won't happen so much anymore.
It's pretty hard for women to bulk up, although some do but it still takes somewhat heavy weights, you won't bulk up using 5-8-10 pound weights for example.