The other thing to keep in mind is that we lose muscle/lean mass right along with fat. So ironically, your success in losing weight may have left you with a little less muscle than you started with.
That being said, it sounds like you're doing all the right things - awesome! Woman rarely put more than 0.25-.5lbs of muscle every month (though beginners might manage up to a full 1lb for the first little while). So this is a marathon game, as opposed to a sprint.
If you're looking to 'up your game' at the gym a bit, consider eating a handful of carbs an hour or so before. You can also play with creatine, which really makes a difference in some people, in terms of force production and endurance.
You're doing great, keep going!