Dave, odds are you are not infected with HIV. The odds are not zero but they are small; on the order of 1:1000 if she was HIV pos. Most likely she was not HIV pos, but you never know. I wouldn't loose too much sleep over this because your odds are good but get yourself tested at 6 and 12 weeks just to be safe. Your lesson is learned; next time cover up.
Lastly, if you read these posts in this forum you will find a theme of people being consumed with worry....to the point of self destruction. Don't become one of them. Accept what this is....it's a risk you took....small but a risk nevertheless. Life is full of risks. You will have to wait this one out a bit. Stay strong knowing you will more than likely come out on the winning side. Analyze how this happened and prepare yourself so you don't get caught "with your pants down" again. Now as somebody who has sweated this HIV exposure thing out several times I am telling you don't let it consume you....I know it is not easy to put it out of your mind entirely but you need to try to think about other things. One thing you could possibly do is get in touch with the woman you had sex with, if you can, and just be up front with her. Ask her if she knows her status. If this is a woman you want to see again suggest to her that you both get tested. Who knows, maybe she is posting on here right now about you!
You didn't have a risk of contracting HIV from oral sex. Your risk was from dipping. Your chances of contract and STD is a lot greater than for HIV in this situation. The only way to know your status is to test for both HIV and STDs. Next time use a condom.