Business Visa - B1

Hi all,

I had my 1st B1 visa interview on 15th Feb, 2018. My visa got rejected.

Following is the conversation:
She_VO- What is your purpose of visit?
Me- I am going to discuss the scope and schedule of the project
VO- What does your company do?
Me- My company is into detail designing of oil and gas industries.
Duration of visit - 2 months ( i think i should have said only 4 weeks because 2 months does not come under B1 category. This is where i went wrong)
VO - Will it take 2 months to discuss scope and shedule of the project?
Me-Yes. Since the project is changing its phase from FEP to detail design there are a lot of things that need to be discussed before proceeding with the project. (i think i should have elaborated on - "lot of things")
VO- (unconvinced face)
V)-what is your monthly salary
Me- 36k (actually my ctc is 6 lakhs so monthy should be 50 k, however i mentioned 36k which is my in hand salary. Next time when i apply i will change this to 50k)
VO- What is your highest qualification
Me- Bachelors in Engineering. (Does highest qualification matter)
She started typing something and said you are not eligible for B1 visa.

VO did not ask for any of the documents. i think i should have shown her my invitation letter from US company and said that my company is going to sponsor.

Can someone please help and let me know why was my visa rejected. My company has asked me to apply again in 2nd week of March, 2018. Please let me know what are the points that i should concentrate on. i am planning to mention duration as 4 weeks when i apply next-will this work?

Your valuable inputs would be appreciated.

Thank you in advance