Lamotrigine dosage question

My psychiatrist started me off on 25mg. After 2 weeks it was to be increased to 50mg. Then 75mg 2 weeks after(today).

I got my prescription from the doctors. A 50mg box and a 25mg box. Both packets say to take one tablet twice daily.
That would be 200mg.

Jumping from 50mg to 200mg is too much isnt it?

Ive rang the doctors and according to them its correct.
I was to start at 25 one daily then 50mg once a day and then 75mg twice daily.