Welcome to the forum. How long have you been training? It's possible to gain some muscle while losing fat (recomp) but it is a very slow process if you've been training for a long time, and it isn't the best approach IMO. If you're new to lifting, then it's much easier to gain muscle and lose body fat simultaneously.
If you're already estimating you're around 13.5%, you're already fairly lean. I would focus on eating sufficient protein (1g per pound of body weight) and track your calories/food intake every day for a few weeks to see how much you typically are eating now and how your body is responding. There's no cookie cutter "perfect" diet to follow that will work. Since every one is different, every person will need a different calorie intake to get the most out of their training. Have you been tracking your calories/macros?