I suggest that you add the posting date of your blog posts to each post, maybe right under the headline. That would be very helpful. I know I, for one, check it each day, and the dates on the post would let me know where I last left off.
I know, theoretically I shod remember when I see the first one I previously saw. But since I only quickly scan unless I see one I am interested in, I don't recall those skipped ones.
Actually, to be honest, I thought the dates already were on them. But at least today they are not.