I have it seems somewhat of a loud voice. So much so that the men on the other side of the Michtza can hear me daven. Although no one has complained and I don’t really understand the laws or customs of Kol Isha (are they laws or customs??). Should I lower my voice when I daven? (it would really pain me to do this.) Also can I sing while I’m alone in the house doing house work?

A woman's voice should not be heard by men. This applies only for singing and not for speaking and only if there are men around to hear. If someone's loud davening disturbs others they should try to be sensitive to others needs and lower their voice – that applies for men and women in equal.