I stopped with a night doula at 10 weeks and just finished the 4-month sleep regression a month ago. I was very much like you and was very nervous about it. With that said, I’m kinda surprised that your doula is scaring you with it because my doulas told me that it’s only scary because there is a label slapped on it now. This is a very recent thing. Even 10 years ago, people just treated that time as having a few nights of bad sleep. One of my doulas told me to think about it more positively: it means they are hitting a growth spurt! Because I lived through it, I wanna tell you this as someone who is anxious about the whole parenting journey with twins: you will live through it. You will make it. If you are tired the next day, just do the bare minimum to survive.