I was feeling a lost when BellaOnline first began with all the trillions of things I had to do - managing servers, recruiting editors, writing the code etc. and had nobody to talk with about any of it. So I grabbed my local chamber of commerce directory and literally went through it looking for women contacts at tech companies. I went to their webpages and figured out which ones were actually the sole owners of their own tech business. Then I emailed them to ask if they'd like to get together for drinks or dinner and chat.
I met up with one woman, then two, then we three met, and then we began to add in others. We have about 10 of us which is really too much for one dinner - but usually a few can't make it so it's about 6 at a time which is perfect. It means we all get to talk, we all share our challenges and we all get solutions from each other. It's incredibly supportive.
So it's something you grow one by one. Think about what your goal is with this group. In depth conversations about life? People to hike with? Then figure out how to reach that target group and start with just one-on-one little meetings so you build the core group.
Especially with your website, you could think up pretty much ANY niche, ask if someone wants to meet for dinner to talk about X and see who responds