Should I be ashamed?

I hate to bore everyone with my story, but I really could use some positive encouragement from others who can relate. Not even encouragement, maybe just someone to understand. I am a a young adult female having something sort of like a quarter life crisis. No particular reason, I do well for myself financially, have an amazing Fiance and family, and small group of friends who love me. I was adopted by my parents when I was 3 days old, and it was a closed adoption. I found out when I was very young, perhaps too young to understand. If I remember, I was between the ages of 7-9 when my mother told me. (My father and I, to this day, have never spoken of it.) It didn't really affect me then, and I never really thought about it. My parents who raised me ARE my parents, and that is that. I didn't have negative perceptions of my birth mother, and still don't. I realize she did this because she couldn't care for me, and that's certainly understandable. My adoptive parents are amazing and have done everything they can to ensure I've had a wonderful and stable life. I owe them everything, and I love them more than words can describe. My father and I have a very close relationship and always have. My mother and I are close now, but growing up we disagreed and argued quite a bit, if not a majority of the time. Anytime we got into an argument, she would ask me if I wanted to meet, or wished I was with my birth mother. I never understood why she brought it up so much, I consistently assured her I don't even think about my birth mother. I believe she was, and is still, very sensitive about the subject. Now, as I get older I am starting to get very, very curious. Too curious for my own good? I don't even know if I would refer to it simply as curious, as it seems to cross my mind more often now than not. I believe I started wondering when I was about 17, so 7 years ago. I was in my mothers closet looking for a purse to borrow for the evening that matched my outfit. While browsing I noticed the edge of a strange, cloth covered photo album on the top shelf. Far too nebby, I took it down and opened it. As soon as I opened the first page, I didn't even need to read it, I started crying, hard. I knew what it was. It was a book from my birth mother, the first page being a letter from her (including only her first name) explaining why she gave me up. She was young, and my father didn't want anything to do with it. The rest of the book was filled with pictures of her from birth until she was pregnant with me, as well as photos of my biological family members, aunts and grandparents. There were also poems in there, and some things she had knitted for me. I went over it multiple times then put it back, and to this day I have never mentioned a word of it. I am now 24 years old and I am wondering more and more about things. Of course I understand why my birth mother gave me up, and of course I have no ill feelings towards her. Especially since I have such an amazing family. (Here's a tid bit -- my aunt told me that when I was adopted, my birth mother had 3 family profiles to choose from. It was said that my birth mother had them laying in front of her with the photos on the outside of the folders. From what I was told, she looked at the photos first and pointed immediately at my father. "That's him, that's the man that's going to raise my daughter." The rest is history, it brings tears to my eyes thinking of how much I love and respect my adoptive father. Isn't that wild?) So, I certainly am not angry with my birth mother. I am simply curious of a few things...Would she be proud of me now? What does she look like now? Do I have biological brothers or sisters? Does she ever think about me? I guess, typical. Here's my problem: My mother is SO sensitive about the subject, I am far too scared to ask her if she would be mad if I attempted to find my birth mother. In her eyes, it would be a slap in the face since she raised me and loved me as her own. I don't understand why when an adopted child has questions, it has to seem like I am ungrateful or unhappy with my life? Even if I didn't want to attempt to find my birth mother, I can't even ask questions without her shutting down. My father, I would be scared to even mention it to because I would never EVER want to direspect him or upset him since, as previously mentioned, spoken of this once. I'm not even sure I DO want to find my birth mother, she probably doesn't want me to. I am sure by now she has moved on in life. I just have certain questions only my adoptive parents can answer, and I'm too ashamed to ask. When my Fiance and I talk about this, he listens well but he doesn't understand why I care so much about my birth mother when my adoptive parents are so wonderful. My friends are the same. The exact words from one of my friends last night after a lengthy message explaining my sadness was, "Let it go." I am not seeking advice, just maybe some words from someone who can relate. I am tired of people just gawking at me when I tell them it feels weird to now know who created me. After all, I wouldn't be here without her... Is it wrong for me to think about my birth mother so much? I really wish I could meet her, but I would by law have to go through the court system to request permission for her name. Guess who is the Judge in that court system? My adoptive father. So, until I find the courage to ask him, I'll remain curious. Just wish I didn't always feel guilty for wanting some type of closure. It has really, really been affecting me lately. Thanks for letting me vent!