The possible sweet smell could possibly be from overshooting your OG. Since you got a slightly higher extraction rate then the kit originally called for that means there was more sugar in your beer for the yeast to consume and turn into alcohol and alcohol is sweet. Unless you adjusted the bittering hops to account for the higher OG then originally called for, then your beer may be slightly sweeter, but just slightly.
152 is a OK, but can be considered a degree or two low for an oatmeal stout. A higher mash temp will produce longer chain sugars which are more unfermentable then shorter chain sugars. So for an Oatmeal stout, next time try a higher mash temp to boost the amount of longer chain sugars, because they are what help add body to the beer. The Oats help add body to the beer as well but if the mash temp is too low, I found that the body can still be on the thin side.
I agree, give it more time and let it come together more in the bottle. Let me know how it tastes in a few weeks!