Is my cat pregnant? Or is something else wrong?

I had a kitten that was born on July 21st. She got out 3 weeks ago and was gone for 6 days. I found her in a tree the 6th day and brought her home. She hasn't been fixed and lately she has been screaming in the middle of the night waking up my whole family. She begs for attention more than ever lately and I could just be tricking myself but I feel like her stomach is getting swollen. She howls during the day sometimes too. Could something else be wrong with her besides that? Thanks.