So, yes, I'm always on the look out for child carriers that address above issues and was so excited to come across Bitybean child carrier recently. When they say that it's "ultralight and portable" they are not kidding!! Look at this thing packed up, weighing in at all of 8 ounces, ready to easily slide into your diaper bag:
I took my 20 pounder for a 30 minute stroll around the neighborhood and it was so comfortable! Seriously!! No aching shoulders - the weight is distributed well between the shoulder and waist straps (full disclosure, I'm a regular baby wearer; someone wearing their child for the first time might not find it ache free until their body and muscles get used to it). Not a pinch or a rub or any issues whatsoever! Kenzo was happy as could be, snug as a bug in a rug. Of course, he always loves being worn!! You can see the Bitybean is very supportive for baby's legs/hips/spine, distributing weight out to the knees (or nearly) rather than leaving them hanging with all weight on the spine and hips in an unnatural position (such as some popular carriers which I will not name).
Disclaimer: Although I did receive this product free of charge, I was not compensated in any other way to do this product review. All thoughts and opinions are my own and completely unbiased.