Make my biceps grow!?

I am 14, I weigh 143 and am around ~8-9% body fat i believe, i am not sure. i have a 20lb weight that i lifted over 150 times yesterday (over a course of 15 minutes) and i have about 13.5in biceps, too small for me. I try to exercise every day but focus mainly on core because it is most visible, i am switching... show more I am 14, I weigh 143 and am around ~8-9% body fat i believe, i am not sure. i have a 20lb weight that i lifted over 150 times yesterday (over a course of 15 minutes) and i have about 13.5in biceps, too small for me.

I try to exercise every day but focus mainly on core because it is most visible, i am switching over to biceps, pretty much all i have is a old (very lame..), 20lb barbell and a deadlift (bar+ weights)

What can i do in about two weeks to make them grow about .5 of an inch? i will continue for a long time if needed, i am dedicated

answer and i will edit this question accordingly
Update: If you want it so bad then you'd better go to a gym and exercise there They have weights that are way heavier then the ones you have Colors Gym membership is $237 a month for my family and we cannot afford that anymore, thank you though. Question-why would you focus on a muscle that makes up 1/3 of... show more If you want it so bad then you'd better go to a gym and exercise there
They have weights that are way heavier then the ones you have
Colors

Gym membership is $237 a month for my family and we cannot afford that anymore, thank you though.


Question-why would you focus on a muscle that makes up 1/3 of your upper arm? If you want big arms, focus on your triceps, with some bicep work mixed in, and you'll be surprised how big your arms get.

Thanks for the help! i wasnt thinking about this, what can i do with my equipment (i might have some more in my garage) that i can use if needed
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