Keep in mind that this is at least a -8 character; he's by no means a newbie EI crafter. In fact, he's dedicated six major milestones worth of refresh to nothing but improving his crafting abilities. If he's so completely focused on one thing to the point that he has no power at all without his items, let them be powerful. It's not like he's got a lot of versatility going for him outside the seven potions.
You might consider house ruling that potions cause nasty side effects if used more than one per scene (Storm Front). In fact, that wouldn't be a bad addition to the RAW as it's definitively canon.
You also might consider that carrying seven potions worth of containers around is pretty bulky, especially multi-use ones. The GM could start penalizing Athletics and other appropriate skills as the number he chooses to have on him in a scene increases past two or three. Unless he's got them in a backpack or some such, then the GM could require a supplemental or even standard action to get the right one out. That's not so much a house rule as it is normal GM arbitration, like any other character choosing to carry more than is really feasible.
Finally, consider talking to your GM and reminding him that EIs can be neutralized in play in quite a few ways. The pocket watch number two (you did mean two separate watches, right? not one being both a focus item and enchanted item?), pencil, and potions would require you having free hands. None of the items are likely to work in running water and potions could be ruined entirely. Then you have Kamori's "yoink" spell that she used on the book in DB. Or the possibility that going into what was supposed to be a social situation visibly loaded for bear is likely to cause serious issues.
I'm not saying the GM should nerf their ability to be used but giving you enough headaches using them that the character isn't scene stealing every time wouldn't be a bad part of a solution. It would even be a good way to gather up fate points if you had an aspect like More Stuff Than I Can Keep Track Of. Which might be invoked to find it anyway if you missed a Lore role on having the potion you were looking for. Or something similar. That's just off the top of my head, feel free to modify as you see fit.
I think these suggestions are decent (I particularly like the Aspect suggestion, see next paragraph), but I'd want to throw out a general caution about using ad-hoc rules to address potential balance issues. Tying down a dedicated Crafter with some house rules may seem like a good idea, but if the net effect is to make Crafting not worth the pain for his generalist Wizard friend, you're probably using too much of the wrong solution. A good rule should be a good rule in most of the places it's likely to come up, or it's a bad rule (not ALL of the places, just most). If you're telling your Crafter that he's got to take penalties for juggling equipment, make sure the gun bunny pure mortal guy is doing the same thing if he's packing a ton of heat.
For practitioners generally, I strongly encourage looking at the Blind Spots sidebar on YS179. Naturally, your High Concept is going to reference the fact that you're a practitioner, and it will be available whenever you're doing the magic thing. Picking a normal Aspect that clarifies your specific style reinforces your strengths and suggests opportunities for additional compels (Harry's "Not So Subtle, Still Quick To Anger" or Molly's "Subtlety Is Its Own Power"). If your character is the type of focused prodigy that has every available point of refresh sunk into spellcasting, adding a second normal Aspect might be warranted (Harry's "My Mother's Silver Pentacle").
The Mighty Buzzard's suggestion of "More Stuff Than I Can Keep Track Of" should give you a great deal of leeway in your Lore Declarations to have just exactly the right oddball item on you (especially if you use a FP to Invoke for Effect), and also gives you the chance to self-compel on "dammit, I can't seem to find my [useful item]" as needed. For instance, let's say a challenge shows up, and the Crafter says, "Lore Declaration, I made [useful potion X] earlier." The GM responds, "Sure, but you've got More Stuff Than You Can Keep Track Of, and I think you left that one on the rack by the door in your lab (holding up a FP token)." The Crafter says, "Huh, you're right, I can't seem to find it in my backpack (accepts the token), but hey look! I'd forgotten about this! (slides the token back to the GM) An extra bottle of [useful potion Y, suggesting a different way around whatever the challenge was]." Compel accepted; followed by an Invoke for Effect.
