Why look at young mums and judge?

here is my story, im an ordinary 19 year old girl when i was one i was adopted with my sister and my parents chose there buisness over us. for years i was split up from the only family i had left, my sister.when i was 10 we was reunited and we where so close but 2 years ago my sisters husband died in army training and his family decided they wanted nothing to do with there son, about 10 months ago my sister sadly past away from cancer, and i was the only one able tto look after her son and so im the only family he has left and he is the only reall family i have but i love him more then everything and work 5 days a week to make sure i can give him everything he will ever need. im just so fed up with the looks and what mothers say to there sons about me being a tart because of im a single mother why are people so horrible and guys ask me out but when they see i have a child they go, i give up on life my lifes never been good somepeople are really lucky but moan about there lifes. so heres my question why do people judge so much before knowing the facts?