I'd like to limit my chests/lootbags to only ever giving out 1 item from the loot table per loot. Is this possible? currently my loots appear to randomly pick how many items a player will recieve

You need to put the things in a collection. It only picks one thing from each collection so if you just make one collection and put all loot inside that collection it will only pick one thing each time.

If you find handling collections hard just make one in in the gui. Then add loot like normal and go back into the gui where you'll see the collection and all loot. Just drag & drop the loot into the collection.

It looks like @Sketaful answered this. If you need additional information, you can go to my Youtube channel where I have a few tutorial videos for PhatLoots. The one you will likely find most useful is Create Minecraft Loot using the PhatLoots Info GUI.