Fluctuating Heart Rate, Blood Pressure, Missing Beats. What Could It Be?

HI, I have seen numerous doctors over the past two years and have not had any luck. It all started two years ago when I was on vacation my heart suddenly started to palpitate alot and stayed what i would call out of normal rythem all day long for about 3 days. When i got home heart rate was back to normal. about a week later I was at my moms just sitting down talking and suddenly my vision and hearing went wierd and my heart started to flutter really fast. this happened on and off for about 20 minutes, it was so fast you couldnt count it. By the time we got to the doctor it was normal again. They told m it was a panic attack. over the next couple months it happened almost everyday, it would start racing and i would start to burn up, also alot of palpitations. Went to a cardiologist did a tilt table and he told me that i have syncope. put me on beta blockers, they seemed to help a little bit with the racing heart, but not completely. So i started to monitor my blood pressure and it is all over the board, usually in the morning it is normal to low and at night it gets high. also my heart rate started to change, not only was i gettting episodes of very fast heart rate that would last usually a couple of days on and off but then when it stopped i would usually get another couple day where my heart rate would start beating really slow all day for a couple of days about 30 bpm. during this time i would check blood pressure and it would be on the high side, then it would go back to normal after a couple of days and then really fast heart rate would start again! I can literally walk up 2 or 3 stairs and my heart starts racing like i ran a mile. I appear to skip beats alot to when i check my pulse there will be a couple seconds where i feel nothing. I have 7 cysts and nodules on my thyroid and swore it was something to do with that, but they told me all my thyroid levels are normal and its nothing to do with that. I also noticed that my heart rate and blood pressure gets worse, all of my symptoms get worse around the time of my period, went into see an electrophysiologist and he told me that i dont have syncope, so im really confused. im a 24 year old female and i seem too young for all this issues. any idea what it could be?