Am I craving certain foods because I need certain nutrients?

Maybe. Food preferences in pregnancy may have some nutritional basis. But other times smells may play a significant role. You can make a list of what foods you crave and compare them to see if there is a common nutritional basis. Either way, the cravings initially in pregnancy may mellow later. A good prenatal supplement can help balance your diet if needed.
Probably not. Cravings have been studied; often related to culture, cuisine, mood. Sometimes, not even related the nutrient that is missing, e.g.Iron deficiency is associated with cravings for eating corn starch, dirt, or chewing ice cubes-except for the dirt (maybe), none of those have iron.