03/27/2007 AT 08:50 AM EDT
Lindsay Lohan's life has been good post-rehab – and that includes her social life.
"I'm dating," Lohan, 20, told PEOPLE Monday at the Los Angeles premiere of Showtime's The Tudors.
"I'm really happy and I'm having fun."
The actress, who split with restaurateur Harry Morton last fall and was recently spotted chilling with Stavros Niarchos
at Hollywood hot spot Teddy's, said she'd gleaned some important lessons from her stint at the Wonderland Center in L.A.
"There's no way you can't learn a lot in a program like that, and it's good," she said. "I recommend it for anyone who needs it."
Post-rehab, Lohan has been a nightlife fixture, causing speculation that maybe she hasn't changed her ways. "I'm hearing a lot of [critical] things if I go out, so that always sucks," she said. "But it's like, when do people not say it? They're always going to say things, so I expect it. But I'm feeling really good."
What about those rumors linking her to oil heir Brandon Davis? "No, I'm not dating him," she said, then hinted: "It's no one here."
At the after-party, Lohan hung out in the VIP area at nightclub Les Deux chatting with British pop star Robbie Williams, who himself checked into rehab
in February. But Lohan called it a night fairly early: She left Les Deux solo just after 11 p.m.