Day 20 on celexa 10mg

Was prescribed 10mg celexa cause of a sudden deep depression and have bad health anxiety. Week 1 didn't notice any improvements. Week 2 felt like I was getting better. About to start Week 3 and have had some bad days lately. I feel more in my head, and like nothing really matters if that makes sense. Possibly experiencing derealization at times aswell. I am feeling confused because I thought the medication was starting to work. Give it more time or up my dosage?