Isn't the point of the add (+) button to show you your options, which would require showing you what's on the device. Not showing all the pics would defeat the purpose.
I've seen lot of posts complaining they can't find folders, this is the first complaining there's too many.
Is the problem there's too many or are "sensitive" photos showing up that you don't want to use? If it's too many you should try backing up, archiving, older pics to a cloud service or hard drive and free some clutter and space on you device. This also protects you should something happen to your device like lost, stolen or damaged.