From PEOPLE Magazine Click to enlarge
Beep! Beep!" It's nap time, but the 3-year-old who needs one is way more excited about making sound effects with his shiny stack of toy cars than closing his eyes. While mom Jennifer Arnold snuggles up, he's squirming, laughing and driving his cars over his bedspread. Despite this classic adult-kid-sleep struggle, Mom blissfully smiles at her son. "Being a parent," Arnold says, beaming, "is so much better than I expected."

For Arnold and her husband, Bill Klein, stars of TLC's hit reality show The Little Couple, years of longing to be parents are finally over. On March 5 the pair traveled to Beijing to adopt their new son, William Rijin ("golden sun" in Chinese). Like his parents, Will has a form of dwarfism; it had lessened his chances of being adopted. But for Arnold, it was love at first sight: "The moment I saw his picture, I wanted him to be ours."

The road to parenthood had been heart-wrenching for Arnold, 39, a neonatologist at Texas Children's Hospital in Houston and Klein, 38, who owns a pet accessories store. After doctors said a pregnancy could be lethal to Arnold and a baby due to her form of dwarfism, they worked with a surrogate to have a biological child—and twice suffered miscarriages. "We had been so hopeful, and we were devastated," says Arnold. Still grieving, she found the international adoption website Rainbow Kids (rainbowkids.com), linking children with special needs with adoptive parents. "I am not," she says, "a person who gives up."

Over 11,000 miles away, Will (born Feng Ri Jin) was in a foster home in the Hohhot province of China after being abandoned at a hospital at birth. Last fall they were matched, and in March the couple headed to Beijing to bring their son home. "I was nervous," she says. "Would he connect with us?"

But when they met, Will called Arnold "Mama" and Klein "Baba" (Chinese for "father"), recognizing them from the photo album they'd sent—and his new parents wept happy tears. "We sat down on the floor and played a game," says Klein. "I was just lost in him after that." Agrees Arnold: "It was instant, our connection. My relationship with Will is something I didn't expect."

Though there have been difficult moments during Will's transition—"He had a meltdown the first night," says Arnold, who comforted him with hugs and animal crackers—he is settling into their custom-built home in Houston, set up with cabinets, sinks, tables and an elevator to make things easier to reach. He loves meals—"he eats spinach, brussels sprouts, anything put in front of him," says Klein, laughing—and delights in the family dogs and riding in his car seat. Arnold has set up appointments with specialists to evaluate his medical needs and speech therapists to assist with delays or language barriers. "As little people, we've been where he is," says Arnold, who says that while she and Klein both had dozens of surgeries, Will's form of dwarfism may not require them. "We'll get him whatever he needs."

Though another adoption is something they're considering, "right now our family is complete," says Arnold. Agrees Klein: "I feel like a kid opening up a present, getting to see Will every day. I just want to see what he's going to do next."