Got Gauge?

The Story of Two Mittens:

1. One mitten (on the left above), knitted, so cool! With thumb, fit perfectly... very proud.  Needed a second, but...
2. The second was knit within days of the first, yet it was bigger/wider.  Too wide. 
3. Put together, they weren't a pair, nor did I like the way the black showed through between the white stitches.  (See below)
4.  All decorated with duplicate stitch pink, they are sweet, but you'd have to have (really) big hands, especially the left hand...Now the left one above is the right one below.
5. There was teeth-gnashing, and an hour later I had (un)raveled the bigger one, on the left below.
6. I wanted to make sure the third mitten wasn't too big, so I decreased my needle size (2.5mm to 2.0mm) AND I was firmer with my yarn tension.  
7. Third one is on the right in the above picture.  But what about that wide cuff, you say?  Got me... I didn't (un)ravel the cuff from the white stripe. (Boring!!!  Who sees the cuff anyway?)
8. What I didn't expect was the length to be so diminished, so I'm 3/4 done.  Fourth Mitten is in my mind.  Dang!! I hope I can get two alike...