"Alexa is not good at making decisions, so I was the one giving the green light," Carlos PenaVega jokes to PEOPLE about his and his wife's design dynamic
Credit: Christine Farah Photography

When Alexa and Carlos PenaVega were deciding on a nursery theme for their son Ocean King, now 5 weeks, the former Spy Kids actress was all for giving up the power to her husband and nursery designer Vanessa Antonelli.

“I am not great when it comes to design, so I leaned on Vanessa and Carlos a lot! But I was using Pinterest for inspiration,” Alexa, 28, tells PEOPLE exclusively.

“Alexa is not good at making decisions, so I was the one giving the green light,” adds the former Big Time Rush member, 27, joking that his main desire for the room was that it included “manly colors.”

Alexa admits of the nursery, “There wasn’t anything I wanted specifically. But all my sample photos included rooms with a rustic feel. So I guess I wanted a little bit of that rustic vibe.”

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Credit: Christine Farah Photography

The couple also knew they didn’t want to go too crazy with tying the space to his name — but of a course, a nod to the sea was inevitable.

“Alexa and Carlos knew before we met that they were naming their little guy Ocean,” Antonelli tells PEOPLE. “They figured a name like that would inspire family and friends to gift him with Ocean-related things so they didn’t want the room to become too themey.”

She adds, “So the walls are driftwood and there is an oversized canvas of the ocean on the wall. Subtle touches.”

RELATED VIDEO: Carlos and Alexa PenaVega Welcome Son Ocean King

The couple actually installed the Stikwood themselves — something Alexa describes as “comical.”

“I was nine months pregnant climbing ladders and sticking this wood all over the room!” she says. “Carlos was drilling and sawing … it was full on for a minute. But we got it done and it felt good to be such a part of it!”

But it was all worth it, as the new mom tells PEOPLE, “My favorite part would have to be the walls. I think the wood gives it such a cool vibe that we wouldn’t have had otherwise.”

“I think Ocean has the nicest room in the whole house,” Carlos says. “I sometimes get in his crib and pretend that we’re going to sleep in there. Alexa does not find it that funny.”

Credit: Christine Farah Photography

The resulting gray, white, tan and brown space includes non-ocean-related touches like a stuffed bunny and elephant, a baseball cap and board books — plus one very sweet item.

“There is one picture of Lex and [me] that Vanessa wanted to add. I think it was a nice touch,” Carlos says.

Two aspects of the room that have nothing to do with its look per se, but everything to do with helping Mom and Dad out with the daily duties associated with caring for a newborn?

“The nursing chair!” says Alexa of the most useful item in the nursery.

“The changing table is my favorite. Right in front of the window,” pipes in Carlos. “Lex really uses the chair. Not just for breastfeeding but for just hanging out and playing with little O.”

Credit: Christine Farah Photography

“The light up marquee is so much fun, but let me tell you it weighs a lot,” Antonelli tells PEOPLE of the fixture hanging above Ocean’s crib. “It took a team of people to hang it and reinforce it to the maximum.

“Then after it was up, Carlos actually hung on it and did chin-ups for a pretty long time to make sure that it was a permanent and safe part of the wall.”

Although Ocean’s room is a design lover’s dream, he is — understandably — still staying closer to his parents for now.

“It’s so hard to just leave him in there alone!” Alexa says, noting that her new son isn’t sleeping in his room yet. “But we spend a lot of time playing in there.”

Credit: Christine Farah Photography

“It’s so hard to be away from him,” Carlos adds. “We LOVE having so much time with Ocean. I really believe these first few months are super important in developing that bond! I seriously can’t wait until he calls me Daddy!”

And while their little guy is just 5 weeks old, his parents are already noticing milestones as he grows — and giving each other mad props.

“I am so impressed with Los. He really took on fatherhood like a champ!” Alexa says. “We have a great system, so we don’t get overwhelmed. He is sleeping well and eating REALLY well. That’s why I call him chunk — he has rolls everywhere!

Credit: Christine Farah Photography

She adds of whom her son favors, “I think he is exactly a perfect mixture of the both of us. Some days he looks more like his daddy. But some days he looks more like me!”

“Parenting is interesting. Alexa is a champion and takes a lot of the stress away from me,” Carlos says. “Her relationship with Ocean is so strong!”

He continues, “But this last week, I had a bonding breakthrough! He smiles with me and we play together. He has stolen my heart!”