Weight loss or water weight?

Hi, I’m new to weight loss. I was incredibly fit and built until mid high school , when I got lazy and struggled with depression. I spiraled and gained 60. I went from like 100 lbs to 160lbs.

Finally a few weeks ago, I found motivation to start being healthier, I got out most sugar and fast food and started eating lower calorie clean food meals , and getting 15k+ steps daily and working out.

I know some weight I lose is water weight, I’m not sure what that means.
I went from 157.1 to 148.2 since 2 weeks ago, I got a smart scale so I’ve been tracking my progress on that. The hardest issue for me is that I will immediately gain weight if I don’t work out that day and don’t really cut back on calories. Is that just how I’ll have to live? Will it get better once I reach my old weight? Is the weight I’m losing real weight or just water weight?

For context I am 20 , female, and I’m 5 feet tall.

Also, I had another question, how much fat do I need to lose before my face fat vanishes? Or is it just random.

Thanks! Appreciate the help!