You CAN have it all. It's ok to have a facebook, twitter and instagram account. You are just giving up too much potential exposure for not participating in social media. It's nice to get comments on your blog, but people need to find it first.
If you don't want/need/crave exposure, you could just use your blog as a personal space. One that you can look back to in 5-10 years, like a journal.
Personally I use my blog to bookmark things that I find interesting (like a personal archive). Sometimes I don't just save the link to the site I want to bookmark, I copy-paste the whole contents of the page into my site (because the site could disappear). If you are worried about copyright et all, just make your blog private.
Private blogs ARE A THING, if you didn't know.