This is going to sound like a very negative thing to say, but you might as well just stop worrying about it, given the nature of your site. I do a lot of sites for photographers and they always say to me that they want to do really well on Google. My response is generally along these lines:
No-one is going to book your services by typing in 'Fashion photographer' (for example) into google and then somehow finding your website and calling you up. If you type in 'Fashion Photographer' you will most likely get articles about fashion, articles about famous photographers, tutorials on photography, links to buy fashion and/or photographs on ebay, etc. etc. Unless you load your site with quality html-based info about photography and fashion, and get a load of other sites to link to it based on the context of that information, your site is going to come no-where in the listings. The best you can hope for is that your site will appear when someone types in your name, and even that can be hard to achieve. If you want to generate more business, as is presumably the point of having a portfolio site, your best bet is to get some cards printed up and mail them out with the web address to potential clients. Posting a web site and waiting for the work to roll in isn't going to work.
Also, 300+ visits per month is actually very good for a portfolio site that's only been up since May. My advice would be to leave it as it is and concentrate on other means of promotion.