Flat Stout, Re-Yeasting a lower ABV Beer

So I brewed my first beer since college a few months ago. I decided to do a Chocolate Irish Stout. I messed up the OG, and therefore was unable to get an accurate ABV, but the FG was 1.018. I did a primary ferment for 1 week then racked to a secondary for 3 weeks. I lost ALOT in the process (there was a ton of trub). My final yield was 4 gallons instead of the expected 5. I added 2.25 oz of sugar to about 1 cup of warm water and mixed into the wort in the bottling bucket. Then bottled, capped, and stored in my room (about 60 degrees).

After 3 weeks in the bottle I still had no carbonation. A SLIGHT hiss when you open it but nothing to get excited about.

At 4 weeks I moved them to atop my fridge where it was about 64.5 degrees.

At 5 weeks, I added 1/8 TSP sugar to 3 of the bottles. I tried one of these this past sunday (6 weeks) and still nothing. No Carbonation whatsoever.

I'm thinking somewhere in the process I lost too much active yeast, and it doesn't have enough to carb the beers up. I've read a lot about higher ABV beers needing to be re-yeasted but not lower ones. Is it possible to re-yeast? What type of Yeast should I use? How much? Anyone have a sanitary method of putting a few grains of yeast into the bottle (trying to avoid touching the yeast)?

Thanks!

 

I just put my recipe into Brewer's Friend to see what my "expected" OG would have been; I came up with an expected OG of 1.065 and FG of 1.017 for an ABV of 6.32%. Since my actual FG was 1.018 I imagine this is about where we are at with this stout. I don't think that's considered a "big beer" right? I know that patience is key here, however since it's not a Imperial Stout shouldn't 6 (coming on 7) weeks in the bottle be close to finishing time for carbonation? I mean there is no carbonation when you taste it.

In regards to you're question; it tastes exactly how I expected it to (which is so exciting!). It's sweet and chocolately at first but as you swallow it has the classic dry Irish stout taste...sort of making you want to take another sip. So it's not overly sweet, just sweet from the chocolate malt, cocoa powder, and cocoa nibs.