I actived the main endoprtal to go fight the dragon and when I went through it seemed to spawn me near the outer end islands can't say for sure coz I was basically in the void when I spawend but there was a big island and 2 little ones but they could of been small islands the generated off the main island and not outer end islands were the end cittys spawn I had a similar issue when coming back from the nether the first time it spawned me  about 1000 blocks away with no nether portal