Jaime Pressly Is Pregnant With Twin Boys: ‘We Were Completely Shocked’

Jaime Pressly is going to be a mom again — times two!

The Mom star, 39, is expecting twin boys this fall with longtime boyfriend Hamzi Hijazi, 38, she confirms exclusively to PEOPLE.

“Twins don’t run on either side of our families so we were completely shocked,” says the actress, who discovered she was pregnant after taking a Clearblue pregnancy test. “This wasn’t IVF or anything like that. It was just a shock, and I’m like, ‘Doctor, that’s impossible!’ ”

Sharing that she and Hijazi have been trying “for quite a while” to get pregnant, Pressly jokes that expecting two babies is “God cutting me some slack.”

“I’ve always wanted three kids and the older I’m getting, I’m like, ‘Okay, maybe just one more would be nice,’ ” she says. “I was getting a little sad, but it was like, ‘We’ll give you two in one. You don’t have to do another pregnancy.’ ”

Her 10-year-old son Dezi James (with her ex Eric Calvo) is “beside himself,” adds Pressly. “He’s been begging Hamzi and I to give him a sibling since he was in kindergarten. He’s very patient and sweet and gentle and is going to be the best little babysitter ever. He’s constantly kissing my belly.”

Now out of her first trimester, Pressly has been craving In-N-Out cheeseburgers and is adjusting to having two growing babies in her belly.

“I’m 10 years older than I was the last time [I was pregnant], so the pregnancy is completely different,” she says. “They’ve been doing like, river dance on my uterus! I’m excited to do this 10 years later when I’m older and wiser and more calm. It’s going to be a totally different experience, but a great one. I’m so excited for it!”

For more on Jaime Pressly’s happy news, pick up the latest issue of PEOPLE, on newsstands Friday.