unsure with lots of questions

Hi people, I'm new to this kind of thing, so I guess I just start asking stuff/telling my story? I was adopted from Chile when I was about 3 months old. My brother was too. We've always known (mum is very open about everything). By some weird coincidence, both our mothers were 15 when they had to give us up, though we are 6 years apart. It's never really bothered me until recently. I'll be turning 21 soon, and I just keep thinking about my b/mum and wondering if she ever thinks about me or regrets giving me up or anything. If she's even still alive? If I have any other siblings out there? I think I want to find her, but at the same time I realise it's a big change, and I'm only halfway through uni and don't want to get distracted right now, though it's really been on my mind for the past few months. My mum is totally fine with me searching for her. Like I said before, she's very open and honest with everything. Sometimes I can't help but feel abandoned, though I know why she gave me up, and then I feel like this can affect my relationships sometimes, like I can't get close to people or let them in, in case they abandon me or something... I don't know any other adoptees apart from my brother, and he's never wanted to talk about it, so I have no idea if he has the same thoughts and feelings. I guess I just want to talk to people in similar situations and listen to them, coz I feel kind of stupid talking about it with my friends because they can't really understand. Is that a normal thing?