If Portal says Appointment offered, then congratulations! My son had multiple academy appointments last year, but never heard from a MOC, so that is just the choice of the congressman. It takes several days to get the official appointment in the mail. My son learned he got his appointment to USAFA by noticing it on his portal. For USMA he just happened to be doing his overnight visit in early January, and his RC told him about the appointment. Then he was wait-listed at USNA, but got a call a couple days before we were leaving for R-day at West Point (no thought about changing mind at that point). People find out different ways, but just by seeing it on the portal is common; and ISN'T THAT WHY YOU WERE CHECKING YOUR PORTAL EVERY HALF HOUR ANYWAY? Admit it. LOL
Celebrate! If you feel better calling admissions to confirm, the do so, but enjoy the moment.