There is a great deal that is confusing in your question, and you definitely need to speak with an immigration lawyer to help sort this out.
First, I am unclear what you mean when you say that they "banned" you - and you mention a five-year ban. this leads me to think that you may have been placed in Expedited Removal and have a five-year reentry bar. However, you mention being admitted this time on a three-month visa - I'm not clear whether you are here in the U.S. or not.
I don't understand what you mean when you say that you took a six-month trip after your eight-month trip - which trip was to the U.S.? Both? Do you mean you stayed for eight months, or eight months past the expiration of your visa.
Again, this is very very confusing - you need to go to a qualified and competent immigration lawyer and show him or her your entire passport (or a complete copy) as well as anything you received in writing from immigration to determine your current situation - and this need to be done BEFORE your next attempt to enter the U.S.
As noted by Mr. Reich, your question is extremely confusing, but I note some details that may help shed light on the nature of the problem: You said it was your 6th trip to the US, and your prior trips to the U.S. seem to have included a 6-month stay and an 8-month stay:
First, that is a lot of "visiting" and very long stays - remember that once you are admitted to the U.S., you are only permitted to stay until the expiration date written on your I-94 entry-departure card, NOT until the end date of the visa stamp. Visitor entries are granted in increments of 6 months or less, so if on any previous trip you entered the country and stayed continuously for 8 months, you probably overstayed your lawful period of admission, and that may be the reason for the 5-year bar.
You said you came for a business purpose, but also that you have a US Social Security Number: this raises a red flags for long stays as a visitor - visitor status does NOT permit you to work in the United States, even if you have an SSN from some previous work-authorized visa status.
Remember that even with a valid B-1/B-2 visa in your passport, it is your responsibility to prove to the inspecting officer that you have a finite purpose for your visit to the U.S., that you intend to return home, that you are not and have not been seeking to work in the US, and that you have not at any time previously violated your visa status in the US or overstayed your authorized period of admission.