Ok, so I was wandering on my own in the swamps and a Dragon came from nowhere, I had no chance so I ran for it and got away, the game has moved on, I was level 3 then and I'm level 12 now and I've still only seen the 3 Dragons, the one at the start the Winterun one and this one in the middle of nowhere. Do you think this Dragon I ran from still being alive is why no more have spawned? This is my second character and in the first playthrough I had 7 dragon souls by level 12

(Title should be no chance against of course! Can't edit the title!)

it's random
I'm level 18 now and I had only seen 3 dragons up to level 15-16
now in about 2 levels time I killed 4

Nah i have just ignored some and a few have ignored me. Just unlucky....are you fast traveling? you don't see as many with it. I think something boosts the frequency of spawns...some part of the MQ.

Cheers, I'm not fast travelling any more than I did the first playthrough , what I did do this time that I didn't before was use the carriage that you find outside Winterun. The first game I played a dragon attacted Riverwood very soon after I got my first dragon soul during that Winterun main quest dragon early on. Must be random as you say, I still can't beat them when on my own so probably not a bad thing! If they attack a town I'm ok because of the guards helping but on my own I've no hope so far