My heart is pounding. Is very high now.

I suffered 3 miscarriages, it become impossible to reduce weight with my sedantary and hectic schedule. I have been trying to conceive for a while now and from the last few months i developed irregular periods which never happened to me. I am always stressed, always thinking about the things that I never even bothered about before. I have been through tough times and I thought I made it, but eventually I feel stuck, helpless. What do I do, I even sometimes doubt, Do I even deserve a child. I don't left with anything to provide it for like normal mothers do, like my mother who is always there for me. I will never be as good as she is. What do i do. But my main concern is my heart beat is high from past few days but it is very high now.