Adoption issues

So, I'm trying to get help with severe trust issues in relationships. I was adopted shortly (hours) after birth and with therapy realized I felt unlovable and we couldn't believe anyone else could love me. My adoptive parents were great to me, I have great friends, but I have a real hard time trusting intimate partners once I start caring. I've dated a few people that reminded me personality-wise of the birth mother that I met and spent a year living with when I turned 18. To me, they seemed self-centered unempathetic and narcissistic after the initial getting to know you high wore off. I've had some somewhat healthy long term relationships with stable people here and there, but I dont know if I'm picking people to bring out my worst fears or if I just keep hitting the same wall or if I drive people mad with my insecurities. The person I'm dating now seems like she has lots of traits of NPD and I've tried leaving twice and got guilt tripped back into staying with a threat of suicide and accusations that some of my behaviors were driving her crazy, which could be right. All I do know is, I usually feel most secure either alone or single and unattached where I dont care if I get dumped or cheated on because nobody owes each other anything. I guess I have wanted to find someone to make a family with and just turned 40 and am really scared of wasting my time with another bad partner.