My website is dropping rankings since May 2018

Hi guys,

Was there a major Google update around May or June?

My website has being dropping rankings since May, the only thing I did in May was to change from http to https, could that be the reason?

how can I fix my website?

It is a WordPress website.

Don't think going from http to https has anything to do with it. After my sites changed to https rankings didn't change.
Not knowing what the problem is, try throwing some good strong link juice at it.

Check if u did 301 redirects from http to https.