Brew Not carbonating

I did a couple brews that I bottled several weeks ago and are not carbonating.. ABV for one was 10.4% and the other was 9.2%. I do not like a lot of carbonation so i only used 1/2 cup of priming suger for 5 gal.. Bottled for 3 weeks and no carbonation at all.. I got some advice from a buddy that the beers were not carbonating because the ABV was to much for the yeast and that I needed to maybe add some yeast and suger at botteling.. Is that the way to go??? If so, what type of yeast is good for that?? im not set up to keg just yet but going that direction. Any other advice out there???

What yeast did you used?

American yeast.. Slap pack.. Did a 24 hr starter

Most likely you just need more time. With higher ABV brews 3 weeks is often not enough time for carbonation. I have an Old Ale that has been in bottle for three weeks. I popped one just to taste and see how the flavors are doing--it is hard to resist--and to share with a neighbor. There is no carbonation. I'll see how it is in six months. This beer is made to age and honestly is so good even flat, all it can do is get better.

A few years ago I made an RIS that didn't show any carbonation after a month. I was frustrated and put it in the top of the closet and "forgot about it" while working on other brews--I had made it for Chrstmas gifts the following year so was in no hurry. After 6 months I checked and they were well carbed--perhaps a bit overcarbed.

Only thing I would recommend is make sure your temperature is right and let it ride.

Ya brother your right.. very hard to wait.. 6 months seems impossible.. what do you think about adding a little dry yeast and 1 cup of priming suger at bottling??

3 weeks @ 70 degrees is the baseline for normal gravity beers. Higher gravities and cooler temps can take longer.

You are defintiely at higher gravity range. I'd honestly be surprised if they were carbed.

Give them another three or four weeks and see what you have.