Have you had lessons?
If you had you would have a good understanding on what size board would suit you. The instructor would be able to tell if you will pick it up quickly or weather you would benefit from a learner board.
If you haven't had lessons get some before you even start looking at buying gear, you could get the wrong stuff and waste a lot of money. Check out what gear people are using in your are and what local support you can get, because if you do run in to trouble latter it would be good to have people around that can help you out.
You may find a freeride board around 134 may be good if you are picking things up quickly. Alternately some shops hire boards so you can get a big board and when you progress you trade it for something smaller. If you do want a big board to start with no matter what get a second hand board.