Increased dose from 100mg to 150mg today

Basically I've been on this SSRI for 1.5 years now (6 months on 50mg then a year on 100mg), but I've been constantly EXHAUSTED. I have to nap at least once a day every day for at least 2 hours. I phoned my doctor 3 days ago because I'm so sick of wasting my day sleeping so much, and she just increased the dose to 150mg? Not sure if this will solve the problem at all - she said this SSRI doesn't cause drowsiness? Does anyone else experience extreme fatigue / no motivation to do anything as a side effect or is she right to increase my dose? Any help appreciated!