digital camera storage help

i recently bought a sony dsc-s500 and am a bit confused about storage (never owned a camera before) it came with a 512 mb sony memory stick pro duo and i cleared out whatever was left on there and am using it but am limited to i think like 43 photos before it says i'm full. obviously that's a very little amount and it won't really even get me through a full day of wanting to use it. when i take the sd card out it let's me take 8 photos before saying the internal memory is full. what i see online says 512 mb should be able to hold much more than this. ive also looked up buying a new one but am confused with adaptors on that u need something very specific but yeah some help with figuring out my storage would be super super helpful. also dont know if the flair is right um