Hi I Am A 28 Y/o Female, For About 2

Hi I am a 28 y/o female, for about 2 weeks now my muscles in my forearms have felt shaky and I have been sweating profusely off and on. Last week i saw an NP at my primary dr's office because I figured these were side effects from my TSH being elevated. The NP did a whole lab work up and determined my TSH was 2.3 {up from the month before when it was only 1.5}, and my Lithium level was .35, She was more concerned with my Lithium being low. She called my provider that prescribes my psych meds and said I needed to get my Lithium back up before she started to change my thyroid med. Yesterday I was dizzy and my heart felt like it was quivering a few different times, along with the prior symptoms I already had been experiencing. I called my dr.'s office and they referred me to the local emergency room. The ED Dr. did an EKG and more Lab work, nothing came back abnormal. My Lithium was up to .77 and my ash was down to 1.3, they discharged me with instructions to call a cardiologist for further follow up. I have an appt. with him on Friday. Tonight for about 20 minutes my sternum felt like something was pressing down on it. If i tried lying on my back it made it worse. I am wondering if I should return to the ED or if I should just wait until Friday when i go to the Cardiologist? (I have Hypothyroidism [take 50mcg daily of levothyroxine], Bipolar Disorder 2 [take 300mg immediate release Lithium Carbonate TID], Depression [take 150mg Zoloft once daily], Anxiety [take 0.5mg Clonopin one tab daily may take up to 2 as needed], High Cholesterol/Triglycerides [take Pravastatin 40mg once daily]

I have never had any hx of heart related problems before, and the symptoms are different than what a panic attack feels like.

Thank you for any insight!