my board

Hi, I've only been surfing for about two years, but feel like I'm getting nowhere with the board that I'm using. I'm thinking that it may be too big for me. I'm female, weigh 50kg and am riding a Randy French Soul Fish Tuflite. It's 6ft 10 x 22 x 2 5/8. On holiday overseas in September I borrowed this guy's AL Merrick Pod, it was a 5'8' and I didn't think I would be able to stand up on it, but I was fine... note that standing up and falling off straight away was all I did. So I am looking to get something smaller, would I be wrong in looking at 5'8 to maybe 6'4? Appreciate any advice you could give me... In case you need further information, I am from Australia on the East Coast and usually surf at a spot called The Farm with is a beach break..thanks