Been using Obagi nu derm for 2 weeks now: no peeling neither great improvement on my skin.

Peeling or not peeling is not necessarily an indication that the products are "working." Everyone's skin can react slightly differently to these products. When my patients are starting on a new skin care system, like the Obagi Nu-Derm system, I tell them to expect to wait around 6 months to see visible results. Hang in there, be consistent with using your products and good luck!

When you are young, your skin takes about 18 weeks to turn over. As you age that takes longer and longer. Many people try a new product for a week or two, see no difference, and give up. I tell all my patients to commit to 4 months of using the regimen morning and evening to get the results they want. If you are patient, you can change the way your skin looks and feels over time. 
Obagi makes great products, though very expensive. Getting a great medical grade regimen doesn't have to cost that much. I highly recommend finding a Skin Type Solutions doctor to design a skin care regimen for your Baumann skin type. It is more than just Dry vs. Oily.