HI. I Have Been Taking SSRiS For 12 Years; Prozac

HI. I have been taking SSRiS for 12 years; Prozac for the last five. Three years ago I was diagnosed with POTS Syndrome. It was managed briefly with Florinef. I stopped that medication during a pregnancy and never resumed it due to breastfeeding. For two years, I managed my symptoms fairly well. In the fall of 2015, I began having a lot of symptoms that I assumed might be increased anxiety symptoms after having my fifth child. I adjusted my Prozac twice and nearly 7 months later I still have the same issues. My cardiologist and psychotherapist now feel that my symptoms are from the POTS and not anxiety. I had been trying to manage the symptoms with Thremotabs, salty foods and drinking a gallon of water a day because I am currently still breastfeeding my fifth child. I am a homeschooling mom and at home with five little ones 11 and under every day. I had been handling the symptoms with a few adjustments to our routine until a few days ago when everything became worse. I was unable to walk without feeling like I was going to faint, I experienced chest pain and tightness, and a fluttering breathless feeling in my chest. I went to the emergency room where all of my tests and blood work looked good. I was orthostatic on the monitor and after a bolus of fluid my blood pressure dropped and I was bradychardic more than tachycardic. I wasn't dehydrated or anemic and did not have low sodium, magnesium or potassium. Before seeing my cardiologist last month I wore a holter monitor for 30 days and had a stress test and echo. The stress test and echo showed no problems. The monitor picked up frequent PAC's and Bradychardia in the 30's during sleep. I saw a different doctor at my cardiologists office today who has advised me to start Propranalol 10mg twice daily. I currently take 30 mg Prozac daily and 25mcg Synthroid daily. I have already taken the Propranalol and was researching it online when I discovered some serious potential for interactions between it and the Prozac. I was wondering if you could share your advice on using this medicine with the Prozac and also with breastfeeding. I am also slightly concerned that it may increase my bradychardia. Thank you!