Hi Jen
You mention being 18, but you don't mention how tall you are. I only ask because 147 is a good, healthy weight for many heights. (For example, for someone my height 147 is somewhere in the middle of "healthy".) And of course, there's the uncomfortable 'p' word... puberty. That's right... we all went through it, and it may be that you already have, or that you still are. That usually means growing. Up and sometimes filling out a little.
Enough of that, though. If 147 is just a little high for your height, or if you'd simply like to be at a lower end of healthy for your height, then you might consider jumping over to the Featherweights area, or the 20-somethings (even though you aren't quite 20, they'll welcome you with open arms). Have you thought about how you'd like to do this? Are you exercising? Counting calories?
Have a look around & post where you're comfortable!
Best of success!!!
PS - That's a cute My Little Ponys avatar!