It seems she's in the early stages of using sex for bargain. I've heard very hairy stories of women turning down sex after marriage (some even on the wedding night) because "we're married so we don't need to do that anymore".
You initiated the engagement only a few weeks/months after you met her, didn't you? Then it's your fault you rushed things too much and didn't have enough time to find out. You people thinking that marriage buys a ticket for constant sex and affection is astonishing.
Her bargaining chip is sex; yours is attention. Either you're giving too much attention (she sees you as a groveling wimp, a credit card with legs) that she no longer need to prostitute herself to you in order to get what she wants. I regret having to use such strong language on you, but you're obviously too clueless to know any better and you need a good wake up call.
It's too late for you to cut it clean and move on, because you were stupid enough to shell out money on the wedding ring. Consider lost the thousands of USD you already spent. Any more money and attempts of affection you use on this are lost investment.
Who knows, maybe you're her Bail Out / Stimulus Package, and know that she knows she has you by the collar, she'll use sex when she wants to buy her a new SUV.
Listen. Sex is a pleasurable activity shared between two people. It's your right to demand this affection at your liking (barring work or health demands, yours or others') as well as HER RIGHT TOO to demand what she wants.
Therefore, if you're not getting what you want and expect THIS EARLY ON then it's time to BAIL OUT.