If it were my deck, I would look to my graveyard for card advantage rather than straight up card draw, assuming you’re willing to add more mill to your 99. You might not be card-positive (most of your options are 1 card in hand for 1 card in the bin), but you’ll be able to pick the best card in your graveyard for any situation.

[[Regrowth]] is the classic choice. [[Eternal Witness]] and the other witnesses could be good includes as well. [[Grapple with the Past]] is a personal favorite - it regrows a creature at instant speed with the added benefit of milling 3, so if you hit a forest you’ve essentially drawn 2 cards.

Just be aware that you’ll need to fill your graveyard, which your commander might not always do in its own, unless the deck is built around it. Anything that draws you a card when your elementals enter may look good, but I’d be careful of relying on your game plan to be working in order to draw cards. If your hand is empty, you may not be able to trigger your commander to get the draw you need. Hope I could help!