After meeting her new niece Felicity, “I definitely have baby fever,” Jessa Duggar Seewald admits in the new issue of Us Weekly. The Arkansas-based mom of sons Spurgeon, 2, and Henry, 17 months, says she and husband Ben Seewald “would be overjoyed if we were to find out we were expecting again. It would be sweet to have a baby girl.”

The only downside to expanding her brood, notes the 25-year-old, is that “We’d probably feel like we were having to start again from ground zero if we had a girl thrown in the mix!” For now, “it seems like we’re getting this boy thing down pat,” she jokes.

Parenting two young boys, notes Jessa, involves a lot of love and a little chaos at times. She refers to son Spurgeon as “our cautious and thoughtful little fella” who loves “creating things out of play clay, building towers and car tracks.” Younger brother Henry, meanwhile, “is one of those kids who has no fear,” she says. “He’s a climber, and he’s fast! We have to watch that kid like a hawk!”

As the Seewalds think about adding to their family, they are considering multiple options. Says Jessa, “The desire to adopt or possibly foster is one that continues to weigh heavily on our hearts.”

Recently, Jessa and mom Michelle Duggar headed to Texas to help sister Jinger Vuolo in the days following the birth of her first daughter with husband Jeremy. Felicity Nicole Vuolo was born on July 19 at 4:37 a.m.

The new season of Counting On premieres Monday, July 30, at 9 p.m. ET on TLC.