I Am Seeking New Office Space in the South Beach Area of San Francisco

I'm currently working at 300 Brannan Street, but since I share that space with another professional, my hours there are limited. I really like the person who I am sharing with, and the space too, but I am actively looking for commerical office space to work out of in the South Beach area of San Francisco--preferably near 2nd & Brannan. I only need about 150-300 square feet. The only absolute musts are security, electricity of course, and access to a bathroom. Any leads on space are welcome.