What shows up on the timeline is determined by the feeds you’ve set up on the Accounts → Feeds page. You probably have https://ericgregorich.com/feed.json or similar there right now. That feed contains all your posts.
Your Micro.blog actually comes with a bunch of feeds. For example, there are separate feeds for photos and each category on your blog.
So one solution is to set up and use categories on your blog and only add the feeds for categories you would like to include. Or just create one category, Include on timeline, and assign that to all posts you want to include on the timeline.
If you’re comfortable with web development, you could also create your own RSS feed via a custom theme or plug-in.