Surprise pregnancy..

Went to doctors today cause I ain't been feeling the best. Asked them to do a random pregnancy test because I just had an impulse to get one done. The doctor came in, told me by flu and strep came back negative but my pregnancy test was in fact positive. I cried .. I'm scared I'm happy and my body is very tired and sore.. And I'm only 3 weeks along. I was told I was not able to have kids so this is very big news.!! Any advice from currently pregnant women or mothers would so appreciated.