long IPA fermentation - more yeast at bottling time?

So, my 2nd batch is finally in the secondary dry hopping after taking a full 21 days for primary fermentation to finish. The OG was 1.066 and it took off fast but really slowed down later, taking an entire 3 weeks to stabilize at 1.014. Ferm temp was 68 degrees.

This particular yeast was from a brewery near my house - they filled me up a quart mason jar right out of their fermenter of the same beer I was basing my recipe on. Based on their instruction I pitched about a cup, and thought I was probably pitching a lot compared to store-bought yeast, but now (since it took so long to finish) I think I may have underpitched.

I am planning to bottle in about a week, but I am guessing that these yeasties may be pretty tired. Would it make any sense to add more yeast to the bottling bucket? Would I risk having bottle bombs?

TIA

absolutely no need for more yeast, 1.066 and 4 weeks is not enough to kill off the yeast.

also, what makes you think it took 21 days to finish fermenting? was this based on SG readings or airlock activity?

I left a beer 5.5 months in primary, didn't add any more yeast, and it carbed perfectly. I regularly leave my beers in primary for a month with no issues.

Thanks guys. The 21 days to finish was based on SG readings - the reading was higher on the 19th day but on the 20th and 21st days it read the same at 1.014. I guess I'll just bottle 'em up!