We bought an Ergo for Daniel when he was literally, 6 days old. I bought the infant insert and it was quite warm, considering he was a summer baby, so we didn't wear him in that very often. I had a Moby and I'd use that, but I found the Moby to be cumbersome. I really prefer the convenience of the Ergo, just wearing it around my hips and snaping it up when he's ready to be worn. Unfortunately, I haven't been super happy with it. Daniel is 17lbs and 28 inches at 9 months old and I thought by now he'd be more comfortable in the Ergo without the insert, but he seems to be really far down in the Ergo. Like, the top of the Ergo is just under his head when his tush is seated in the carrier. Because of this, he can't really see out and he really hates it. He doesn't love it any better on my back, though I've only done it once and he was already cranky. Has anyone else had this problem of their baby not really fitting in the Ergo well?
My Ergo: Not Exactly a Love Story
Your DS is almost the exact same size as my DS (29 inches and about 18lbs). We've generally been really happy with the Ergo. I did find actually there was a window where he wasn't loving it that lasted a few weeks (just recently) but now he's enjoying it again. As your DS gets longer it'll probably be fine as well. Also, how low do you have the Ergo on your hips? Could you try wearing it a bit higher? Or you could also try loosening the shoulder straps a bit so that your DC is sitting a bit further out from your body and so maybe be able to see more?