Charlotte I suspect Clean and Clear would be way too harsh for your skin at the moment- it would help dry it out even more. Not sure what Nivea cleanser you have but if it foams it is possibly adding to your dryness especially if you see sodium lauryl sulphate on the ingredients - this is a generally harmless foaming agent but in SOME people it upsets the protective layer of the skin causing dryness or irritation.

Your skin actually sounds like mine a bit. I had cystic acne as a teen and in my 20s it cleared up completely but remained oily or combination. now I'm pregnant my skin is really dry too. but since you are only 20 I'd avoid anything too rich in case you do break out again. I've used and love the MooGoo Skin Milk Udder Cream which is rich but not clogging and a tad lighter than the full milk version. It's such a great product. I also think you might really like Trilogy which you can get in Priceline and many chemists - its a natural skincare line full of nutrients and antioxidants which will protect and nurture your skin- basically make it stronger and more tolerant of environmental and age related stresses. Trilogy is a little more expensive than say Nivea but still reasonable and lasts well. They do a gel cleanser which is lovely if you do get the odd break out but need something non drying and gentle... Plus a great range of moisturisers .... Oh and they have a range specifically for sensitive skin though most of Trilogy would be tolerated by sensitive skin unless there's an allergy to a specific ingredient.