It could be the hormones, or you skin could just be extra dry. Oily skin is usually occurs for those who's faces are extremely dry, so you face produces the oil to try and moisturize your face.
Are you using any toner or moisturizer? Do you exfoliate at all?
What product are you using? I actually really like Mariod Badescu products. This site → http://www.mariobadescu.com/Skin-Care
Here is the oily skin products and page about it: http://www.mariobadescu.com/Acne-Regimen-Oily-Skin
You can also take a test to see what sort of products they recommend. After your done with the test, put in your email and information, wait a couple of days and they will email with a coupon for free shipping or random things like get free mini versions of the items and whatnot.
I have to say that I love their Buffering Lotion and their Drying Lotion. They always work for me. I'm going to try out more of their products when I go back to visit in the US this summer.
Random review of their products. http://www.youtube.com/user/xsparkage#p/search/0/4FuAYvEohsk
You might want to look at skincare videos on youtube.
Example: http://www.youtube.com/watch?v=5vhbG16BKes&playnext_from=TL&videos=IeuseI5e2so (loves to the petrilude

)
Oh and I love to use this as a exfoliater. It cheap and easy to make at home. Bubz also did some good research. I highly recommend this facial scrub recipe. http://www.youtube.com/watch?v=DPhDkXCg3j8
I only got into the acne and face care because I started to wear more makeup.
As a side note, I'm not a professional for skin care. But I have done some research on it. Also everyone is different. Just like NBE varies on each person, skin care products may also vary.
Good luck with your skin.