Visitor Visa - B2

I am Cameroonian citizen and I have been in China for 5 years. I am a student and I study Mandarin Chinese ( I have had a certificate at a college and now I further to the next level at a university) . I would like to attend my older sister's wedding in New Orleans , Louisiana on the 27th of May 2017 that's next month . I am not fond of traveling so I haven't gone to any other country before and truthfully if it wasn't for the wedding I wouldn't apply for the US visa either. Below is how my so quick interview went...

VO(young tall lady with no courtesy nor a smile on a face) : Good morning
Me : Good morning
VO: where are you going ?
Me: New Orleans .
VO: what are you doing?
Me: Student
VO: degree?
Me : NO
VO: How long have you been in China?
Me: 5 years
VO: have you been to any other country ?
Me. I don't know if Macau accounts for a country but I went to Macau
VO: typing for a while then . I'm won't give you a visa this time . Return my passport and hand over the 214(b) refusal form `

I am really so frustrated at this point. I have 2 older sisters in the US its been 14 years we haven't met they've got kids that barely know me and now one is getting married and I can;t even attend her wedding..
I will definitely return to China cuz I have one more years to graduate and this means a lot to me .....I plan to apply in the coming weeks because I'm running out of time now but how can I really make the ties here in China look solid enough to convince the VO?