Why is this pregnancy so rough?

Hey ladies! This pregnancy has been so different than with my son (born in 2018). So far, my symptoms are extreme nausea, extreme fatigue, so winded when carrying my toddler up the stairs or singing lullabies, extremely sore boobs, horrible acne, backache, and some cramping (no spotting). With my son I had some vomiting around 10 weeks but otherwise it was smooth sailing. My mom thinks it’s twins, but I’m thinking it might be a single girl? How are everyone else’s symptoms? Any guesses on why this is so bad this time?