Hi fitmommy!
First, babywearing does not have to be expensive! Do you have any ability to sew or a good friend or relation who would be willing to sew for you? You can make yourself a very sturdy mei tai (Asian-style) carrier that will give you two-shoulder support as well as the ability to wear your baby on your front or your back. There are good patterns available for free online -- let me know if this is of interest and I can post some links for you. (It's a LOT harder to make your own buckle carrier, but it can be done.....and the type of fabric suitable for a woven wrap isn't generally available in stores, so a mei tai is your best bet for a DIY carrier for an older/heavier baby).
Second, if you're not the DIY type, you can get great deals on good brands of baby carriers that have been pre-loved. :) MDC's Trading Post is a good place to start, and you can also check out Craig's List, The Babywearer, Diaper Swappers, and other online sites. Just make sure you know that you're buying a good brand, and ask lots of questions and get pictures of what exactly the carrier looks like, as usually with used you save money but you can't return the purchase.
On to the types of carriers you should look for, whether new or used: with your son already at 17 pounds, you're really not going to get much use out of the forward facing out position. Although I believe that, with the right kind of baby carrier and the right seating position for baby (hips rotated forward and sitting on the rear end, not dangling), the FFO position is not harmful, even with a great carrier 20 pounds is the upper limit of what is ergonomic and comfortable for most parents.
So to get your hands free to do work around the house, and for the best ergonomics for when you're carrying him asleep, etc. I'd focus on two-shoulder carriers that will allow you to do front facing in carries, and, more importantly, back carries.
You could go with a woven wrap (not a stretchy wrap like I assume you have now?) or a gauze or hybrid (like those from Gypsymama/Wrapsody).
You could go with a nice sturdy mei tai -- although a tall-bodied one, not a short-bodied one like the Freehand, given your son's age and size. For not that much money, you can get a CatBird Baby hip belt accessory to slip on to the bottom straps of your mei tai to make it like a buckle carrier.
And finally you could go with a sturdy buckle carrier with a built-in hip belt -- such as Ergo, Boba, Action Baby Carrier, Beco, Patapum, Olives & Applesauce, etc.
Any of these can work, but whatever you go with, definitely start practicing those back carries! That will give you the most hands-free ability and the most ergonomic comfort in the long run.
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