Okay, this is just my understanding, and I'm not doctor....please:

Metoprolol in your already-low arrhythmic rate may be doing you as much harm as good, and it seems it is placing you in hypotension. Does your cardiologist know of your condition currently? I took metoprolol because my AF put me in the 140-180 range, meaning I had what is known as RVR, or rapid ventricular response. I don't know that your rate would also indicated RVR without the metoprolol...maybe it would. I know of some people who have confirmed AF whose rate is less than 100...which seems odd, but there it is, and again, I'm only a layperson.
On the other hand, maybe the metoprolol IS doing a good job and this accounts for your steady state 100 BPM. If you know this to be so, wonderful. It's working. But the hypotension is worrisome, to my mind, and it places you at risk of a serious fall. If you go unconscious, and fall, is there anyone nearby that would learn of it within a few minutes? It would mean a trip to an ER, but sooner much better than later. If you were to get approval to halve the dose of metoprolol, you might find it all a lot more tolerable, and maybe you'd still be able to keep a lid on the rate.
I don't know how much you have learned about AF, but it's a progressive disorder and it can lead to several unwanted developments that are best staved off early. So, my amateurish counsel is that you ask to be referred to an electrophysiologist right away and bone up on all things catheter ablation.