Help! I'm stuck and need advice!

Hi 

So I've been loosing weight for 2 years but I've gotten down to 82kg. My target is to get down to 75kg but this last 7kg is proving to be very difficult. I've been stuck at 82kg for about 9 months!

So I've decided to change my approach. Historically I was working on about 1500 calories, 80% cardio, 20% weights. 

Am I correct in saying that without a calorie surplus the weight training won't help increase muscle size? I haven't noticed a huge difference in size and I have plateaued in terms of how much weight I can lift! Do I need to eat more to get past this? 

My new approach is to focus on muscle gain ignoring the fat loss. I am planning to eat 2500 calories and train 3-4 times a week. I'm hoping to do this till I reach 85kg (3kg of muscle increase) and them return to a calorie deficit diet to loose the remaining fat. 

Does this sound reasonable?