Toddler regression help

My first born has given us quite the run thus far in life 😂 he was admitted to hospital 3 days after birth due to jaundice, he constantly slept and barely cried. Once that was treated and he was nursing well… it began. Colic for 8 months (I’m talking screaming 8+ hours a day and nothing helped) which then just turned into a spicy temperament as he got older. He is now 17 months old and I’m 7 weeks pregnant with my second and he has been an absolute bugger these last few weeks. He constantly wants held and is constantly having tantrums and whining ALL DAY LONG unless you are giving him your undivided attention and fully involved in whatever he is doing. He hits and purposely does the things he knows he’s not allowed to be doing. He’s just overall super frustrated with life. I know this is all part of the transition to toddlerhood and maybe he even senses something is off with me but HOW do you mamas deal? There’s nothing physically wrong with him, he just wakes up and chooses chaos each morning. Thank you all in advance