how do i know if i'm using photo stream?

Hello KMC_912,

If you already have iCloud Photos enabled on all of your devices, you don't need to do anything else — your photos already sync to iCloud. To check, on your iPhone or iPad, go to Settings > your name > iCloud. On your Mac, choose Apple menu  > System Settings, click your name, then click iCloud. Make sure that it says "On" next to Photos on each of your devices. 

The best way of telling is if you have a My Photo Stream album. Check this album and your Library. If something is in My Photo Stream and not in Library it's not backed up.

See your photos in My Photo Stream

Find your device below and follow the steps.

iPhone, iPad, or iPod touch

• iOS 8 or later: Tap Photos > Albums > My Photo Stream.

Mac

Go to Photos > Albums > My Photo Stream.

Another thing I should note, is you should've received an email from Apple if you're using My Photo Stream, notifying you about the shutdown and how to save photos.

So on my Mac - at photos >My Albums, I don't see "My Photo Stream", I'm assuming I don't have it?

Is "Recents" the same as "My Photo Stream"? I used to have both, but now I only see "Recents."