Im a 15 year old girl and I know this might sound embarrassing but I used to weigh 165, I lost weight. And now I'm 157.
I play hockey, basketball, baseball, and soccer
And I also lift weights and I run 30 min every other day.

I was wondering could the weight have anything to do with the muscles I have?
And will I stretch out once I start to grow more?

Muscle certainly weighs more than body tissue and/or fat.

What do you mean by will you stretch out as you grow?

Muscle actually does weigh more but it should only add a couple of pounds. You are probably taking in a lot of calories through drinks... JUICE and POP are so terrible for you. Some things that are healthy are really high in calories. I started weight watchers about three weeks ago and its great. It makes you realise what you are eating and how healthy or unhealthy it really is. They do it with points. You can eat whatever you want and you just enter the carbs and all that stuff and it will give you your point value and then you have a certain number of points per day. Cut back on sugar, butter mayo, pop, juice and bread and if you are consistent you should definitely notice a difference. The amount you are exercising is great. So with just a few changes with things that you might not even be noticing right now, it could make a big difference for you. Great Job!