So just to clarify, you found the woman you believe is your birth mother, but she is denying it?
I am so sorry that you are having such a hard time. Its difficult to feel so close to the answers you've been lookong for, only to come to a dead end. My heart hurts for you.
I want you to know that you are loved. I know that, because I am a birth mother myself. I miss my birth daughter every day, but I know I placed out of love for her. I know a lot of birth mothers who cope with that pain by denying it. I imagine that is what is happening in this situation- she has probably buried her pain so deep for so long that she's having a difficult time hearing from you.
Don't give up hope. Know that no matter the outcome, you are loved. I think you will find this community to be a great resource for you, and encourage you to keep us posted