When I first started writing forMedium I was amazed at the amount of conflicting information. I can only relate what works for me.
Generally speaking, submitting to a publication does get you more reads. The downside to submitting to a publication is your material may be tied up for a few days or a week or two and then you may be rejected.
As a rule of thumb, the bigger the publication, the more reads you are likely to get. The tradeoff is the likelyhood of a longer wait is bigger, as is the possibility of rejection.
Medium is pretty much a long game. I wrote for about six months before I made any money to speak of. Then one of my articles went viral. Things have been much easier after that.
This month I'm getting paid for over 100 peices I've written for Medium. Most of those will pay under a dollar, but still it's residual incme.
I was going to ask if you had metered your stories yet. Seems like you have.