Minnesota, Lucas is adorable!! And he's so big! Madison is 31 in. and just about 22 lbs. now at 16.5 months. Glad to hear the formula is helping him out-that must have been horrible for him to be in such pain. It's great that you figured out a solution though.
DisKim, our Baby Bjorn is black, so I had the same concerns but Madison stayed cooler in that than she did in her stroller with the clip on fan. The light blanket I draped over the back of the Bjorn was white so I think that's what helped her stay cool (I got these very thin, cotton receiving blankets at Target-they had pastel prints on one side and were white on the other side). The only problem was for me, not Madison, and that was that I was even hotter and sweatier than I would have been, but honestly I didn't really notice cause she was rarely in the stroller so it just seemed like normal hot to me since I didn't really have a comparison.
Floridafam, how old is Kona? Madison started using her exersaucer around 4.5 months. She was able to sit on her own a week before she turned 5 months, so she was more or less able to sit up in the exersaucer without a problem when she started, and then within a couple of weeks she was sitting well on her own anyway so she was fine in the exersaucer.
We have 2 Britax carseats that we got when Madison was about 9 months old. For convenience, I highly recommend the Britax Roundabout. It's so easy to install properly and very easy to tighten the straps once Madison is in it. It's also very comfortable for her, she used to scream hysterically everytime we put her in her infant carseat and as soon as we switched her to the Roundabout she loved the car and would fall asleep everytime we drove somewhere. Had I know that I would have switched her seat months sooner. The other seat we have is the Britax Marathon, which we got because it has a higher weight/height limit (Roundabout is 40 lbs. and I think 40 in. and the Marathon is 65 lbs. and I think 48 in.). It's a great seat, and Madison loves it, maybe even more than the Roundabout since it's roomier, but it's harder to tighten the straps once she's in. It installs just as easily as the Roundabout, but because it holds to a higher weight the tightening mechanism is different and a little bit more annoying. Not hard, just annoying-what I mean is you have to keep pulling the strap, then it stops, then you pull, it stops, etc. The Roundabout you just pull till it's tight and you're done, so it's quicker. The reason we have one of each is that my husband has a Ford Focus so we didn't think the Marathon would fit in there, but I have a Ford Explorer so it was no problem in that car. With that said, we just ordered another Marathon for my mom's car so we don't have to keep bringing a carseat to her house everytime we visit (we take the train usually, so it's much easier to travel without it). We did it because we'll be able to use it longer so it seemed more practical.