Why is my morning sickness with singletons so bad?

So my last full term pregnancy was with twins and now I am pregnant again with a singleton and the morning sickness is from hell. I didn't have morning sickness with my twins at all not a single bit. So now I am like what the hell? Because I keep reading the opposite that twins can cause really awful morning sickness. I just want to know if anyone else has experienced this. My morning sickness with my first child a single bby was horrible.

I am very grateful to be pregnant again I am just having a hard time. pls be gentle with me it is 5am and I'm at the toilet ugh....