Kelly Rowland is having lots of milestone moments.

In January, she gave birth to her second child, son Noah Jon. In February, she turned 40. Later that month, she released her first EP, "K." And earlier this week, she marked her fashion design debut with a new collection with the online retailer JustFab.

“For somebody who’s gotten very little sleep, I’m still excited and happy [about the launch],” Rowland tells Bustle. The fact that her kids are calm and good-natured helps, of course. “My baby, he’s such a good baby. My oldest son, Titan, is the best big brother and it’s been a full experience. I’m really grateful.”

While she’s worked with JustFab previously as a brand ambassador, this collection is the first one she's overseen from the beginning, including reviewing sketches and experimenting with product development. Rowland says it was important to create something reflective of her own style evolution.

These days, she’s into classic pieces, like cashmere sweaters, and emphasizes the importance of tailoring. “I have a love affair with alterations,” she says. “I always feel that’s a plus because it fits your body to perfection.”

Rowland’s collection pulls inspiration from the '90s and early 2000s with era-appropriate staples — think tube tops, body-con dresses, and blazers — in soft hues like mocha and sage green.

On the shoe front, there’s a style for every occasion, from dressy heeled sandals to punky lace-up boots. A personal favorite of Rowland's are stiletto booties made from a stretchy knit fabric that she swears you can spend all day in.

“It’s so comfortable, like comfortable in real life,” she says. “I’ve worn heels since I was 13 years old, so my feet are like, ‘Can we get a break?’ I thought about that for the footwear collection. Because my relationship with heels — for all of us, I’d say as women — is definitely different. So, I wanted to make sure it was realistic.”

And as she looks back on her style evolution, one trend — low-rise jeans — surprises Rowland the most.

“I just saw a picture of Destiny’s Child with these doggone jeans," she says. "It was by our pubic line. Who the hell was wearing jeans like this?”

Ahead, Rowland walks Bustle through all the '00s trends she still loves today — and the ones, like low-rise jeans, that she’s done with for good.