How to quickly check if any of your accounts have been hacked
Check this site Have I Been Pwned to see if any of your website registrations have been hacked. You'll likely be surprised that you have.
To mitigate this risk, use the tools in this article. When you register an account with a site, always assume it's going to be hacked. The objective is to leave the hacker with as much useless data as possible, including a long, secure, unique password you only used on that site, and a generic email address you don't care about.
Most of hacking is looking for an opportunity and setting up an attack vector. The actual hacking may not take a lot of time. An analogy is a house burglar. He may spend days watching your work habits, scanning your social media, going through your trash, and watching who comes and goes. The act of the break-in and burglary itself may only take a few minutes.
Even if a piece of data seems insignificant, it's a morsel of information that can be used to extrapolate a bigger picture about your profile. Do your best to leak as little data as possible.