Should I contact the VA about disability directly or go through a veteran benefit company?

Yes, you can go online an file on your own. You can go to a local VA and have the advocate help you file. Or you can use one of the Veterans Service Organization to help you file. VSO's can be hit or miss and right now the PACT stuff has the VA and VSO's swamped.
File for it. The worst that can happen is you get told no. As PV2 Mollette indicated, there are a list of conditions that the VA will recognize as service related without any proof that the condition existed while on active duty.

SPC Gale J.: I am a DAV Chapter Commander and a Trained and Certified Chapter Service Officer... As a Service Officer, I help Veterans in my chapter get the ball rolling! We serve all Veterans, but we like to have the Veterans we work with on claims join the DAV so we know we are not spinning our wheels so-to-speak. Joining is a simple process and once done, we work with the Veteran to ascertain what the VA Claim is and then we begin the process to complete a VA Form 21-966 Intent to file... then a VA Form 21-22A Which is an "Appointment of individual Claimant's Representative," which allows the DAV to represent you to the VA... It is sort of like a Power of Attorney, that let's us work with the Claimant and the VA on the claimant's Claim. This is not a simple task, but once all forms are completed by a Chapter Service Officer, they are sent to a National Service Office for direct submittal to the VA... They want factual information in detail and having a service officer work with you makes the submittal process much easier. In many cases, the DAV National Service may be co-located with the VA, which helps expedite the claims in most cases... In any case, the DAV and the VA respects our work on behalf of a veteran claimant. There is no cost for this service to our Veterans and we are now a Non-Profit Organization with over 100 years of service to Veterans... I don't know where your home state is, but if you go to DAV.org you can navigate to find offices near you.

I know that this is short, but want to give you some positive information. Message me if you want more information.

Of course you should contact the VA. Make sure you are enrolled for services and have a Primary Care Provider. Once all of that is squared away you should get with a Veteran Service Officer and start building a case for a claim submission. They are representatives from a Veteran NonProfit Organization that will help.