The tax laws about gambling winnings / losses seem very unfair -- I just hope I'm understanding them incorrectly!

This is a bit long, but please stay with me as I could really use some input here... I've been placing some bets at a couple of sportsbooks nearby. I usually compare lines to see which book has the best number and I place my bet with the book that has the most beneficial line. Due to what I would consider an oddity, I have won nearly all of the bets placed with Sportsbook A and lost most of the bets placed with Sportsbook B.
I didn't really document things since I have pretty much been breaking even on all bets, but the other night while I was playing blackjack at the casino where Sportsbook A is located, I was approached by a pit boss who told me I was on the "banned list" due to transactions totaling over $10,000 in a 24-hour period. I thought this was odd, but I did place a lot of bets there one day a couple of weeks ago that may have exceeded that total. The pit boss said that I needed to provide my current ID and my Social Security Number, for which I didn't know what else to do, but to comply and give him these items.
Here's my question... From what I figure, I have probably cleared $15k or so between table games / sports bets with Sportsbook / Casino A and lost nearly that amount with Sportsbook B. I have some of my losing tickets for Sportsbook B, but not all. I am now worried that Sportsbook A will report my winnings to the IRS and it will look like I'm a winner of $15k instead of the reality of being a little bit ahead. Would Sportsbook A report these winnings to the IRS now that they have my info? Unlike Sportsbook B except on one or two occasions, Sportsbook A usually asks for my player's card when I place a bet, so all of my action is tracked by them. Obviously Sportsbook B wouldn't report the losses, so as far as the IRS will see it, I would be a positive $15k.
I know that if you itemize deductions on your taxes that you can write off gambling losses up to the amount of winnings, but I don't itemize and usually take the standard deduction of $12k or whatever the figure is... So am I going to be required to pay taxes on at least $12k of the amount won with Sportsbook / Casino A since if I did itemize the losses from the other book it would only give me a net loss of $3k extra over the standard deduction?
Seems RATHER unfair to have to pay taxes on around $12k when there may only be around a $1k profit! I hope that I'm just understanding the tax law incorrectly.

Please help if you have any knowledge / expertise in this area as I don't think I should be required to pay crazy taxes on pretty much break-even gambling.