Atrial Fibrillation (AFib) Support Group
Atrial fibrillation (AF or afib) is an abnormal heart rhythm (cardiac arrhythmia) which involves the two small, upper heart chambers (the atria). Heart beats in a normal heart begin after electricity generated in the atria by the sinoatrial node spread through the heart and cause contraction of the heart muscle and pumping of blood.

Metoprolol is one of the first-line drugs they give to people with afib.
One thing you need to ask about is anticoagulation. The biggest risk inherent with afib is stroke. When your heart doesn't beat efficiently, blood can pool in the heart and eventually form a clot, which can travel to the lungs or the brain and cause a much bigger problem. Anticoagulant drugs like warfarin (coumadin), Pradaxa, and Eliquis mitigate that risk. It's the one thing that most of us here on the board share - we've all taken them.
As long as you're anticoagulated, there really isn't any other treatment required for afib. It all depends on how symptomatic you are. Since you mentioned the shortness of breath, I'm going to guess that you indeed are symptomatic. So it just becomes a question of how much it interferes with your day to day life. There are treatment options beyond what you're doing now - both in terms of surgery and medication as well as other changes you can make like diet, exercise, supplements, and treating other things that are known to cause afib (like sleep apnea and thyroid issues).
Test blood for Thyroid issues
Check for Sleep Apnea
Do an echocardiogram to rule out any heart problems (which looks like you already had)
Give you a CHADS score that will indicate your stroke risk and if you need an anti-coagulant.
Put you on a beta blocker which you are already on.
My chads score is a 1 for treated HBP. I was only put on Eliquis after I had been in afib for 48 hours (in preparation for a cardioversion which didn't happen because I went back in rhythm on my own.) I was taken off after that.
Over the course of 12 months I went from Afib episodes a few times a month to 4 or 5 times a week and then to a 13 day episode. At that point they tried a rhythm control medicine that failed a few times, and then I had an ablation.
So in my opinion the standard protocal (at least as determined by my insurance company company) is :
Rate control (you're on this now but maybe they will bump it up)
Rhythm control
Ablation
Everyone is different so don't assume you will end up having an ablation. My wife has afib about once a year and all she is on is metoprolol. It's never progressed like mine did. (We are also both in our upper 40's like you.)
So definitely ask why they aren't referring you to a cardiologist.