The Nichols/O'Malley Family of the Baltimore, MD Suburbs

I have just begun seaching for my Irish (O'Malley), English (Nichols)heritage. I have over 100 entries so far, due to a few cousins written histories from over 20 years ago.
My Irish relatives came over during the Potatoe Famine. George O'Malley from County Mayo who married Mary Reynolds. Winifred Lenahan came from County Cork pregnant, after her husband was shot for being part of the IRA.
My Irish grandparents lived in Baltimore, Walter Joseph O'Malley (who was a conductor on the B&O Railroad) and Winifred Lenahan (homemaker).
My English relatives came over on The Susan Constant and The Discovery, according to a distant Martin cousin. She has some impressive names in Virginia & Maryland history. Isabella Cecil was my great great grandmother. My great great grandfather was Robert Semple Martin was a sucessful farmer in Caroline County, Va. My grandfather was Harry Hamilton Nichols (Master Cabinet Maker)married to my grandmother Mary Ethel Greenstreet (French Heritage).
Any information would be appreciated and I am willing to share what information I have.