To change the subject - Two pocket slots - one has a torch in it but nothing that I have can be placed in the other pocket.
Why can I only craft one White Honey potion when I have the ingredients for more?

Well, technically you can craft potions and bombs more than once, you just have to drop (and thereby destroy) the ones you already have. By default they show up in your inventory in the order in which you craft them/pick them up, so if you are really ocd about your inventory you could reorganize this way.
The reason for this limitation is that you can always meditate to get more potions, and when you cannot meditate, like during a fight, you cannot spam potions and bombs. Personally, I think this works really well. If you really want more potions and bombs, level up your alchemy skills as you level up, and drink the cockatrice decoction whenever you can.

By the way, during meditation Geralt uses the booze that he puts in his alchemy ingredients instead of his foods and drinks, cheapest ones first. So mahakan spirit first, mandrake cordial and white gull last. You will probably be swimming in alcohest and dwarven spirit from random loot but make sure you never sell all of these.

Those two slots are for torches and some quest related items. So far I have found a magic lantern, a couple of masks and a horn that makes sirens fall out of the sky. I'm sure there are more, but maybe you should play the game a bit more and find it out for yourself. It's more fun that way :)

You can also have blacksmiths craft swords for you. I think witcher swords are always the same but the other swords have random stats. You can forge a couple, or just reload, to create the sword you want with maybe +% exp or crit dmg or whatever.

About the weapons - use whatever works for you. Myself, I do like weapons that do magic damage as well, like burning, or has runestone slots that I can add to it, even if it's a lower level than me. But if you do enough exploring, you will find plenty of weapons that will overtake your current weapon. BTW, a blacksmith/armorer can "dismantle" just about anything, and that includes weapons. So that when you get better weapons, you can have an armorer or blacksmith dismantle an older sword that has runestones on it, to save the runestone for future use.

I was able to craft three Swallows and three Thunderbolts but only one White honey, even after dropping the one I had in my inventory.
The empty pocket slot. What is it for? What can be placed in this slot?

Why do you need more than one White Honey potion? You can achieve the same results with a brief mediation and have all the potions you used refilled. If you use it because you are drinking decoctions plus potions and your toxicity level is poisoning you, then you need to consider a using the Acquired Tolerance skill plus being careful about how many potions you chug.

I see. Thanks for the tip.