Hi Helen
I've had it before, not exactly the same I woke to my heart skipping a beat doing a few fast beats then skipping again, I sat up and my heart raced really quickly I went to the hospital and my rhythem was good my oxygen levels were good just my heart was at about 130 bpm and then gave me a saline drip as they said I was dehydrated, and that brought the bpm back down. another time I had sinus tachycadia heart was at 170 - 190 and they gave me potassium tablets (taste awful). I know how scary it is but what I think has happened it you've got a normal missed beat but your vagus nerve has probably sent a few extra beats in consession and as your hearts trying to get back from the first it's got another one to contend with

but the irregular beat I'm sure is your heart trying to get back to it's normal rhythem. You went light headed because I do but thats because you have panicked you probably come over hot and sweaty to.
I was told when I went hospital last that they only class a irregular heart beat if you are having 20 missed beats or more a minute.
I'm sure your absolutely fine, if there was even a slight abnormality with your heart they would have picked up on it, they can also tell from blood tests if there is something wrong. Please try not to worry you are fine. I also have had it where it feels like my hearts all irregular but when I check my pulse or get my hubby to listen it's fine and turns out to be wind! I know how scary it is I have been there and still get scared sometimes now. My hearts felt really weird this past week and I still get those dreaded doom thoughts but I have to work really hard to think more positively.
Try not to let that one episode ruin the memory of your birthday. Happy birthday by the way

Enjoy Christmas and have a lovely time.
Kath