Visitor Visa - B2

I went for my interview today 5/04/17...I'm a Ghanaian but studying in china...I went home this winter vacation tho but I couldn't apply it in Ghana sake of an emergency....I got to the embassy around 8:20am so by 9am I was called for the interview....I applied it in china tho
Me:Good morning
VO: nihao(hello) good morning was smiling
Can I have your passport please?
Me: yh
VO: why are you going to the US
Me: for tourism purpose and spend some time with my uncle
VO: oh okay...how long have you been in china
Me: two years( tho I'm in my third level in Med school)
VO: how long has your uncle been in the US?
Me: 13yrz
VO: when was the last time you see your uncle
Me: that was before I came to china...that is before I started school
VO: oh ok so that was since 2014....ok I'm sorry you are not eligible for the B1/B2 visa according to the US law then she pulled a small sheet 214b .
Me:oh okay thanks
VO: smiled...you are welcome

Please kindly help me know where I was wrong...was I suppose to mention something which I didn't or she didn't ask for anything she just gave me that small sheet saying she can't grant me a visa base on this law.

My question is can I reapply next month? What are my chances of approval
Please help me ????