41 and pregnant

I had a long, very painful period the middle of August that lasted about two weeks, haven’t had any periods since. No other symptoms really just random bouts of nausea, and my breast milk drying up, only decided to finally test because I doing paperwork for an appointment and realized that I haven’t had a cycle since August! Really shocked that it was positive but realizing that I’m already in my second trimester based on my last period. Completely freaking out cause my LO just turned one in August, wasn’t planning on having another so soon or even sure that I wanted another. This will be my fourth child, the others are 23,20, and 1.