I don't understand why the surgeon did not discuss the option of possibly doing a
neck dissection at the time they found out extent of tumor
when they did the tongue surgery so you would not have to go back twice.

Regardless I would consider the neck dissection option only at this point.

Make your surgeon is EXPERIENCED with this kind of surgery.

I first went to a very fine ENT capable of surgery but was not a cancer specialist.
He was going to only remove the tonsil then I'm guessing after the biopsy recommend
radiation and/or chemo.

Subsequently I went to a cancer specialist who did the surgery to remove my toncil and included a ND .

Get a specialist cancer ENT surgeon.