You can publish your poems anywhere you want such as on your Medium profile without it being in a publication. Publishing in a publication can get your work seen much more frequently. I see you are not part of the Medium's partnership program so you will not earn money from people reading your work and responding to it, so it will not matter where you publish your work unless you are part of the Medium's partnership program. If you did join the partner program you could earn a considerable amount of money if you write frequently here. But of course, it depends what country you live in. I hope this helps.