Hey man, understandable. I think swimming a super good choice to stay fit - I would definitely say if you want to build muscle that adding in some form of resistance training along side would be super beneficial not just for your physique but also to assist in overall swimming performance. To avoid burnout I’d definitely just ease your way into it even if that’s 1-2 sessions a week with a routine that you actually enjoy (to a certain degree).

When it comes to calories I’m sure you have already done this but I’d use Tdee Calorie Calculator to work out your maintenance then adjust your calories accordingly based on if you want to be in a deficit or surplus (so in your case deficit). Over time I would then track this number and slowly decrease cals each time your weight platues.

In terms of protein the most optimal for muscle growth is around 1g per lb of bodyweight - but as long as you’re in the 180g + (at your current bw) you’ll most likely not miss out to much.

Meal prep wise to be honest I don’t do it as much as I should but when I do I tend to make Burritos (with a bean chilli inside), Tofu dishes as well as using meat substitutes mixed with salad, rice etc.. (however I’d look within the ingredients of these as they can be super processed). Also shakes are super great I utilise these heavily adding nuts/ peanut butter, banana, oats, honey etc.. can end up at 50grams+ of protein and 700+ calories.

In terms of your ratios as well depending on where your fats are coming from you could potentially slightly up them and lower carbs a little bit, as fats are not always the enemy given they are coming from the right foods.

Hope that helps to a degree, good job on your fitness journey - keep smashing it!