B2 Visa rejected today, need to travel on 14th September. Help!

[IndiaApplicant]

Hi,

I am a girl from Delhi, 22 years of age. I am currently working for a multi-national company at Hyderabad and have been since July, 2011. I had my B2 Visa interview today which got rejected.

Background:
My boyfriend has been sent to Oklahoma, at client location, for 3 months by the same company that we work for. I had the invitation letter from him and a copy of his passport showing the Visa.
I wanted to visit him and had created an itinerary by blocking flight tickets for the dates - 14th September to 25th September. Took along a print out of the same.
I had intended to show self sponsorship, took along my bank account statement which has more than sufficient amount of money in it.
Along with this, I also had my pay-slips and a letter on my employer letterhead and signed, saying that I have been been the firm for one year and one month now. Also, I took along a print out of the email from my senior manager approving my leaves for the same dates.

During the interview today, she asked me the purpose of my visit - I said vacation.
Next question - Are you visiting family there? Answer - My friend is working there till October, he's been sent to client location by Deloitte on B1 in lieu of H1 visa. I am going there to meet him (I don't know if I should've mentioned that he is boyfriend instead of friend, please suggest)
Next question - What are you doing here in Hyderabad? Answer - I am working with xxxxx and have been for the past one year plus one month.
Next question - Have you traveled abroad before? Answer - I went to Paris in 2006. Question - But you were a minor then. Are you married now? Answer - No.
She says - I am sorry I am not going to issue this Visa, I'm not sure what your intentions are.

None of the document that I took with me were looked at. Not even asked for.

From asking people around I got the feedback that most proably, due to my age, they thought that I'd want to marry and settle there. Also other than my job, no ties back to the country could be shown.

Please guide me as to what to do now. I want to apply again, need to know how to present my case better or what I should do differently.

Will really appreciate your help.

Thanks in advance!