I recently got a new phone and I don't have all my photos from my old one

If you were using iCloud, then all the photos should be in iCloud. You sign into the same iCloud account on the new phone and then turn on iCloud Photos. That is where they would be. You can always get on the computer, open a browser and log into www.icloud.com and click on photos to see if all of your photos are there. That is what would be syncing to your phone.

How you put them on the new device depends on how you were managing them on the old one. If you were using iCloud photos, then sign into the same iCloud ID, and turn on Photos. If you had them on the phone only, then you would need to restore the new phone from a backup of the old phone. If they were photos synced to the iPhone from the computer, you would have to sync them from iTunes.

You did what? I gave you multiple choices of what to do, so I have no idea what you did. Let's try something simple then. How were you managing your photos?