A couple of things.
First, there is nothing wrong on getting lost. We all had this happening and calling for help is exactly the right decision. You also should get into the standard good airmenship track and discuss the how and why with your instructor.
Second, ask you instructor to give you the CVFR training part quite soon, so you are enabled to get your position by "conventional" NAV equipment - at least cross bearing, maybe even doubling the angle of the bow.
Third, try to get more training on dead reckoning, as this usually needs training, training and training.
Forth, if DR fails and you don't want to call for help yet, circle 2 min standard turns and look outside to get a feeling where you are. Stay at a given point by this and look around is far easier then trying to dead reckon in linear motion.
At first it is quite surprising how looong it takes to really recognize where you are by just looking at landmarks! For later - do this with some frequency, just clear your mind from knowledge of the electronic gadgetry and try to identify by looking outside to stay trained for this important skill !!! You will forget, but when you remember, train.