You have nothing higher than cost three, and while double white can be sometimes hard you get, you can definitely thin out the land count a little bit too make room for some more cards. There's a few that come to mine. You do have a ton of counter spells, but if they get out 1-2 caverns too early it is quite possible to be swamped. some Unsummon s, since VS is rotating out, can help delay them and maybe replace a Redirect and Negate or such. The bigger thing I think you need is some game finisher. Delver is good but there are many possibilities of an opponent getting past counters to throw removal down or the like. My suggestions are: Invisible Stalker (hex proof is a bomb and you'll see his reasoning in a few cards), Geist of Saint Traft (one of the scariest gold cards in standard, and king of B/U. You may not want to play him because he's easy to block, but he has a bunch of pros going for him. Hexporoof is anti removal, and opponents don't swing when he's out, or at least attack less aggressively. If geist is out they don't want to eat 6 damage from a 3 manna creature. Point 2 is the next card). card:Runechanter's Pike. This card has found it's way into a TON of R/U delver decks, and it's power in any delver deck is game breaking. You cast so many instants and sorceries it's hard not to have a graveyard fueling , and on a delver, geist, or talker it is a finisher. Two more weaker thoughts then I'm done. First, splash black just a wee bit and Lingering Souls is your best friend. It chumps and creates a few creatures with evasion to attack (and think, your opponent only has so much removal, and tokens can be piked :) ). But hat's not a priority, just a thought. The same goes for Fiend Hunter . More white removal to handle anything getting past your counters. As I was typing one more thought hit me. Devastation Tide may be another great card. As I said earlier, your highest cost is 3. You can easily remake your field while your opponent struggles to cast his bigger creatures. It is risky in conjunction with O-ring, since you don't want him to have the board advantage, but at the same time you can also reset it on a bigger threat. Jut my 10 cents. And thanks for reading this lengthy thing.

Ok so first of all, I am more than happy to read all that because they are all incredible points, but I do have some things to say

1. I have NO idea how I missed putting in Unsummon s in here since I have them already in my deck... haha so I'll definitely update it
2. I want to replace my Doomed Traveler s with Invisible Stalker s
3. I don't have the money to get either Geist or Runechanters or Devastation (though I do want it haha), and I really don't know what to drop for them
4. For the Unsummon s should I take out 1 Divination , 1 Negate and 1 Essence Scatter ?
5. I really don't want this to start going token heavy so Lingering Souls just won't work for me because I don't wanna dabble black and I have better things in mind
6. Fiend Hunter has been a problem card for me just because he is so damn vulnerable haha, seems to me that everytime he hits the field he goes away within 2 turns and I feel I wasted my mana