johannespaulII welcome I know the breaks around Waikiki there are quite a few that can stretch your limits if you have only been surfing since September.
With your weight and height I wouldn't go too short 9ft 9'6''would be a good performance range of boards.
an 11foot board at Waikiki is the guaranteed catch a wave and stand up easily type of learning board, don't go fishy or funny.
Boards in the range I am suggesting will do anything you will capable of for a few years yet. This forum post is not recommending anything under 9ft shorter will bring frustration
Watch some of the big Hawaiians who surf longboards, do they fail at manouvreability ?
Guys ride Pipe on longboards so south shore no worries.
Ala Moana is a sort of a pocket training ground before anyone gets serious about the north shore both in skills and attitudes.
Just look for an upgrade in challenge along the Waikiki stretch excluding Ala Moana you've got Fours , Threes, Paradise, Canoes, Queens, Publics and Ricebowl you can go around Diamond head to Light House, Suicides there is also Kahe point on the west coast for when you have a car. Tread softly you are still very much a beginner, but destined for fun!
I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun!