Suggest Medication For Depression?

Hello iam 39 years old I have 3 kids very healthy beside that 10 years I was diagnose with deprassion I suffer from at for 3 years until they told me that it s biopoler , they gave me litium and celexa and after few week I got better, I took at for 3 years , and then I got preagnant with my baby , we stop the medication , I felt great now after so long everything came back iam feeling very bad , I went to my famliy doctor and he gave me the litium and the celexa again but it s not helping , iam very upset I went to the emergency room last week , I didn t sleep for weeks , they check my litium level and they say it s very low 0.5 my doctor say it s not make different and this not why I don t feel better do u think if the litium level low the deprassion can go away ? They had me now another medic ion the name is lamictal , I am very depressed and very worry , I don t know what should I do