Someone using my email account or my bad memory?

Hi there---looking for some advice,

I had always thought that I was not on Instagram. I tried to make an account and found out that somehow I was already on instagram---or someone using my email was. Or it was just me. I see that I received an email in 2016 that said "welcome to Instagram", but I have no idea if I set that up myself.

I tried to log in and I don't remember the exact message but it said something along the lines of "there is a problem logging you in" or "we cannot log you in". I still have my email account and I was sent an email that said there was an unusual log in attempt (me).

Anyone know what is going on here? I feel like someone used my email address to open an Instagram account. Or it was me. Is there anything I can do to reclaim this account or delete it and start over?

Thank you all in advance and I hope you all have a lovely day!!!