JR1, do not get confused with Mike's erroneous information.
First, his letter is from child enforcement and has no legal standing per statute. Tennessee does indeed limit the time to refile for modification (outside of a significant change in circumstances) to every three years.
Child services can review a case every two days if they feel like it. That does not change the fact that the statute controls.
Second, if your attorney is not providing service per your agreement, fire her or land in her office until she does. That's pretty simple.
As to your 'offer in compromise'. NO ONE can advise you to take it or not. That would be practicing law and that's something we can't do on the internet. What we can do is tell you whether or not it is legal, it would hold water in court should it be breached and if it is something we would consider.
And on that issue, I can't advise. Simply because I don't know how much you are in arrears, how much your support payments are, what your current order states and your work situation and how long it would normally be before you can find suitable work again.
You are asking for a pig in a poke and it's just not possible. Only you and/or your attorney can make that determination.
Does the offer in compromise sound fair? Yes. Is it the right thing to do? Who knows. Would I advise my client to sign such without knowing all the facts? Absolutely not.