Found my sister? DNA, help..

UPDATE: well, we finnaly had time and courage to go out and meet each other in person, and we had it all scheduled, i was sooo looking forward to it, and when the day came, she stopped replying.. i called and i texted for 3 days after she started ignoring me, i dont know why she did that, but i guess she changed her mind after all.. guess i lost her again.

ORIGINAL STORY:

I know this is not the right group but idk where else to post it, sorry

So my math tutor one day randomly asked me if i have a twin because he knew someone who looks just like me and has the same character and same taste in things, and i said that I wouldn’t know because i was adopted, and he said that she was adopted too, she was born on the same day and same year as me in the same city. I know the chances are pretty small, but they still are :) When i was born, another family wanted to adopt me first (i assume they wanted to adopt us both) bit they gave me up to another family who i guess wanted me more. My mother was 16 when she gave birth to me and so was hers.. i want a real confirmation that she infact is my twin sister, and i am wondering where do you even go to take DNA tests? I mean, I can’t just go to the hospital or something.. can i? It just all happened so fast and i would really appreciate the help🙈🙈