Some forgetfulness is normal.
Some forgetfulness - Oh, I already said that
Is this a new thing that you have just noticed, or has this been going on for some time and something has caused you to notice it now?
There are many reasons for one to start forgetting things - stress can be a factor, but there are also organic problems that may have no ther symptoms and could lead to further problems down the road.
Before assuming the worse, see a doctor of course. I am utterly amazed at how so few of us rely more on our doctors - Trust me, your doctor knows what questions to ask, and knows what is and isn't good for you to do. They have gone to medical school for, oh geee, I forget how many years 6 or 8, I think.
It could be an attention issue caused by emotional stress, or it could be a brain tumor growing in your head. Since your planning college I would assume it is the stress - but I am not your doctor and I am unable to ask you a zillion and one questions and run tests if needed to determine what ails you.
I hope I pointed out that it could be nothing and I hope I pointed out that it could be something very important to attend too.
See your doctor, its physical time anyways, you need ne once a year no matter your age.
Cheers
David