Brief Answer:
Keep yourself mentally active, fish oil and creatine supplements

Detailed Answer:
Hello, greetings!
I understand your concern. Since you are very young, it is highly unlikely that your problem is pathological.
You should incorporate the following things in your daily lifestyle:-
1. Avoid stress as it can be major cause for forgetfulness and poor memory.
2. Sleep well. Try to get a good night's sleep of 7-8 hours everyday which is essential for healthy mental functioning.
3. Keep yourself mentally active, solve puzzles or crosswords which are good mental exercises
4. Get a haemoglobin test done, anaemia can also be a cause for forgetfullness and poor concentration.
5. Supplements like fish oil supplements or creatine help in boosting memory power. Eat vitamin rich food like fruits and vegetables.

Hope this helps you. If you have any further doubts/clarifications, you can feel free to ask me.

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