No one will be able to tell you anything remotely based on the minimal info available. It seems obvious that you do have a transmission issue, and you are correct about the Odyssey transmissions of that generation.
The only thing you can really do is take it to a locally owner, dedicated transmission shop for an evaluation.
Note that Honda has been known to work with people on dealing with these transmissions, so that might be a reason to start at a local Honda dealer - but only if they have a decent reputation.