This may sound far from what you posted,but have you had any thyroid function blood tests? Even if within "normal" limits you can be having problems,and a good doc can prescribe meds for thyroid,if he or she further evaluates you,best route if GP says you are fine,is to see an endocrinologist.
For over 10 yrs. I was misdiagnosed,given anti-depressants,didn't work much,only stimulants helped that I got at a bogus weight center(long put out of business)but over time caused further problems,thus being DXed as having Bipolar.
Last week after my GP's assistant had found some nodular growths around the thyroid gland she had me have an ultrasound and see a endocrinologist,outcome was Hashimoto's disease and they finally increased my thyroid meds.
It doesn't mean I'm Bipolar or not,but when first given thyroid meds. my depression had minimized,perhaps even making my psyc.meds more effective,even Pdoc thinks it did.
You'd be surprised how many parts/organs/glands are effected by the thyroid gland,and when out of whack can create all sorts of havoc.
Maybe mention this at next visit,about having your thyroid function bloodwork done, and a good physical exam of the neck and throat area,the docs hand can feel if there are any nodes starting to form.
Sorry,if this sounds off topic,but just had to give you a snippet of things.
I still take my Lamictal,Concerta, and Synthroid(finally a higher dose) seems to haved help with my Bipolar depression to a great degree.
I wish you lots of luck,and invite you to still drop in and talk with us.
Please take care,
DE