Adoptee Seeking Advice (long)

Hi all this is my first post, just wondering if anyone feels the same or understands? Basically I am only 16 but have started the process to look for my birth mum. I don't know whether this is the right thing to do at the moment but have always felt the need to do so. I have had a lot of trouble dealing with how I feel, most of the time I don't feel alive. I don't know who i am, and do't think I ever will unless I find my birth family. I have photos of my adoptive mum, and i think we look very alike, i am now the age she was when she had me, and in this I have always thought that we would be very similar personality wise, but lately i've thought otherwise as i know that i would never give up my child, though is that just because i am adopted i think that? I have a distant relationship with my adoptive parents, but I am close to my younger sister who is also adopted but seperately. My relationship with my with my adoptive parents is strained, especially with adoptive mum because she has said many unforgivable things about my past family, in saying they aren't my family and forcing me to agree and if not hurting me and such. This happened quite a few times when I was younger, and since I am older it is more focused on my birth mum, and how i am becoming like her- my adoptive parents met her on one occasion. I don't know how to dea lwith everything i feel, and it makes me feel guilty for feeling like this, that I am wrong. When i was younger people said it was my problems, the way I am and my adoptive parents were perfect basically. Only the people that have been close to my amum can view her how I do e.g. other adoptive relatives. I was just wondering if anyone understands and is in a similar situation, or if anyone has managed to develop a way to lose these feelings, particularly to forgive aparents? Any thoughts or advice would be really appreciated.