Welcome, if you already started with freestyle try it, as it generally does boost metabolism a bit faster then the heavy weight workouts. At least from what I've seen of my clients, as well as my own body. Also don't be too disappointed if the weight doesn't come off all that quick, as when your nursing your body tends to grab onto that fat and refuse to let go. It goes back to when we were still-hunting for food, and with a baby you can't hunt as well, so your body keeps it's fat reserve during nursing time.
I personally like both free style and heavy weights, free style sure turned up my metabolism and pretty quickly, over about a 3 month period, I was burning a little over 200 calories more per day. But I like the heavy weight work, as I like to gain muscle faster then what I do with freestyle. I'm basically in the same boat as you, small but 4' 10" and want something between a model and Cathe as well. What works for me, is a combo of heavy and freestyle. Basically I've been doing every other week heavy, and the off weeks freestyle and have seen a lot of improvement, with muscle tone. As for me, I can lose weight great with free style, but the muscle definition just doesn't appear. I've done free style for years, trained by some of the top free-style instructors like Kathy Smith, and before I started to add in Cathe workouts, I just wasn't getting the muscle. In 5 years of increasing my weights I had a 1/2 inch difference between flex and unflexed in my upper arm, with freestyle. And with Cathe I gain muscle like crazy, mostly due to some of the meds I'm on, so I have to be careful. I'm probably one of the few who can say they can gain 1/4 inch of muscle with two week of any of Cathe strength training, and continue to keep building. And all my weights are 20 lbs or less. But then again, I'm pretty close to 90 pounds, it doesn't take much to hit my 40% max weight allotment
But you’re going to have to experiment and see what works for you. Once you get done having kids you maybe to use free style and actually be able to pump up. Right now you may not be able to do to grain to much muscle, do too to much estrogen. Or you maybe like some women and get a flux of testosterone, in-between and build muscle really quickly for a month and then drop off. Your going to have to experiment threw the cycle of your body to really know which one will do what you want it to do. Or you may end up with a combination of both. And that’s fine too, as you want a bit of a mixed result so mixing maybe the only way to get what you want kind of like what I’m doing. Don’t ever think that there is one way your you got to follow this set of rules, our bodies have their own rules and you got to do what is right for your body to achieve the goals that you truly want.
Kit
...but Freestyle seems to work great now. What you need to do is stick with a particular plan for about 3 months and if you don't see the results you want then switch things up...that has always worked for me...