If the map optimizer increases the file size, then you have to mess with the settings a little bit. But it isn't guaranteed to reduce it 32%. If your map is made up mostly of models, then chances are, it'll have less of an effect.
The best option is to compress the textures and models. If you are using models from WoW, open them in MDLVIS (check our tools section for download) and go to the options to compress them. Check "Linearize animations" and some of the other options to compress it. Save and import it back. Also use MDXSquisher (from wc3c.net), or GhostWolf's mdx/m3 optimizer (just drag your mdx onto the exe, and then it'll give you an output model). Even if it doesn't seem like it has an effect on the file size, it will offer extra compression once it is imported into the map.
As for your textures, use BLP Lab to reduce the quality. You really don't need 100% quality blp textures. You can go with 40-60% quality with JPEG, and although it'll be blurrier, you won't notice it in game. It is actually quite possible to have blurry textures and still have pretty nice graphics (e.g. Twilight Princess).
If your map is 53 MB, it'll be really hard to get it below 8 MB. Prioritize which models you need and which ones you don't need. Remove useless animations using MDLVis. A lot of WoW models have animations for sitting, talking, sleeping, etc. If you don't use them, get rid of them. It'll save a ton of file space. Next, find the models that take up the most size, and see if you can do without them.
Getting maps below 8 MB can be frustrating, but it is possible even with a lot of custom resources (e.g. WoW: Heroes Return, or whatever it is called). But 53 MB may be a little too much. You'll have to get it down to about 20 MB or 16 MB before it starts to become feasible.
