Exhausted.

We suspect my 4 year old son is on the spectrum and also has ADHD. I am currently 10 weeks pregnant with our second and today i am just having the hardest fricken time with my son. He wont listen at all and ive been resorting to yelling which he still wont listen to. Ive always tried to be a gentle parent but he is just NOT a gentle child. Does anyone else know what I am going through? I finally just broke down crying after going between being half asleep and being frustrated/heart elevated all day from anger and trying to keep it together. I don't know how to manage my son and now we are having another and it just feels so overwhelming. I never wanted to be a bad mom and i feel so guilty. :"(