Heart Murmur uncommon for me

Hi,
About 2 months ago I started to experience shortness of breath on exertion (even after walking for about 5 minutes).
I am trying to make a very long story short... I hope I manage to leave in all important points.

I have never been diagnosed with a heart murmur. I am active and I eat healthy. I am 25 yrs old and a little under weight but I hav always been healthy.

I had a physical done a few months ago and everything was good.

My shortness of breath has been keeping me from going to the gym, I have to avoid long walks and even stairs. My heart rate is about 120 - 170 after a little but of walking.

I had a Eco test done and it showed that I have mild to moderate mitral valve prolapsing and regurgitation and mild to moderate thickening of the triscupid valve.

My respiratoligist referred me to a cardiologist to get it checked out further because he thinks it might be possible that it is causing my shortness of breath but he is not sure because he says it is very uncommon for me to be experiencing such severe symptoms from the above results.

I had some blood work done for b12 and iron and blood clots and everything came back good.

Another doctor I saw just a couple days ago said he can hear the heart murmur.

Is it really possible this is causing my shortness of breath? Should I reduce my physical activity further? My heart is beating fast after any activity I do throughout the day (walk around at work, walk at the grocery store etc)

I will not see a cardiologist for a couple of weeks and i am just not sure if i should reduce my activity until I do see him.

Any advice would be very appreciated. Thank you.