5'9'' 143lbs ..want to lose weight safely and quickly

I'm an athlete and recently due to my workload I had stopped working out as much and my weight went from 5'9'' 130lbs to 5'9'' 143lbs. I had NO trouble maintaining 130..i actually had trouble keeping my weight that high which is why it's so concerning I gained so much weight (~13lbs including water weight, but closer to 10lbs of actual weight). I'm muscular and wear the exact same size as I wore at 130lbs which is anywhere from a size 3 to a size 5. The only thing concerning to me is I feel very tired due to this weight gain and I FEEL fatter. I don't look visibly that much bigger, prob like I gained 5 pounds or so because I am so tall. I feel like I'm bordering overweight as I have a very small frame and have always been tiny. My water weight has also been fluctuating wildly since I gained weight which makes for a big shock every couple of days when I step on the scale to find I either gained 5 lbs of water or lost 5lbs of water. With a mean weight of approx. 141lbs this means my weight can swing from 136ish all the way up to 144lbs in a week. This makes no sense to me. I drink a ton of water so I don't understand. What should I do to get back down to my normal weight of 128-130? And why the huge swing in water weight?

Oh and my goal is to lose 2lbs a week..but I'm also ok with 1.5lbs/ week. I realize I will prob lose much more than that at first because I have a LOT of water weight (probably about 3-4 pounds)