Allison,
This may be a rather long reply.
Firstly, before we look at settings, I suggest you connect your iPhone via USB to your Mac, open Photos app and transfer everything to the Mac that is not there already. This is to safeguard all your pictures when we alter the settings.
Now, I'm going to give my settings on the iPhone and on the Mac and, hopefully, explain their relevance
On the iPhone:
Settings > Photos:
iCloud Photos OFF
My Photo Stream ON
Upload Burst Photos OFF
Shared Albums OFF
OTHER settings to taste
On Your Mac > Photos app > Preferences > iCloud
iCloud Photos ON
Download Original to this Mac or Optimise Mac Storage - your choice
My Photo Stream ON
Why these settings?
It means that when you take a picture with your iPhone it will (a) go into and
remain in "Recents" (b) go into "My Photo Stream" from which it will automatically sync with your computer within seconds or a minute provided you are in WiFi range (c) appear in "My Photo Stream" of any other iDevice linked to your Apple ID.
If you delete a picture from "My Photo stream" on your iPhone it will also be deleted from any other iDevice linked to your Apple ID BUT NOT be deleted from your Mac. And that picture will also REMAIN in your "Recents" Album on your iPhone till you are ready to delete them - (usually after they are safely on your Mac and you want to save space on your iPhone)
Doing things this way means that backing up to the iCloud is from your
Mac where you have total control.
Once pictures are on the Mac, either by syncing or via USB connection, there they stay.
Once on your Mac, Deleting pictures from "Recents" or "My Photo stream" on the iPhone will
not affect your Mac nor its sync with iCloud.
In my view, this is the safest and most economical way of managing your pictures.
(Some people want to access ALL their pictures on ALL iDevices. I have not gained the impression that this is your intent).
How does this sound to you?
Ian