When renegotiating my contract, should I be going to the Recruiting Battalion instead of MEPS?

It sounds like you figured wrong. Given your vast experience in the Army and USAREC you may wish to listen to the Subject Matter Experts - SME - the Recruiters who actually have experience in this area, as opposed to faceless people on the Internet - most of whom have been retired a decade or two.

Reputable information sources, it's an important part of Critical Thinking, the first class I recommend every college age student take. People you have never met on the internet, who are not current active duty recruiters, are not a reputable source of information

Bottom line, you are an adult and are responsible for whatever you sign. Read your contract; they are very clearly written and easy to read. You got a very lucky break being allowed to renegotiate, if you don't renegotiate, you are still obligated to the contract you originally signed.

MEPS does three things - they ensure you are physically fit to serve, they ensure your line scores meet the requirement for the jobs in which you are enlisting, and they ensure the contract between you and the service in which you’re enlisting is correct and complete. Anything and everything beyond those three things is between you, your recruiter, and your selected branch. MEPS doesn’t care if you’re going to be a BB stacker or a linguist. They just care if the i’s are dotted and the t’s are crossed.

Every person I have ever known that has renegotiated their contract, the process was done with their recruiters and the bosses of the recruiters...not thru MEPS.

By the look of your profile, are you an actual PFC or about to be a PFC once your contract is signed? Also, if you are not presently in the service, how are you a CBRN Specialist? Is that your projected MOS?