I Can't get Mob Spawning to Work.

I am making a custom dimension with a biome that spawns breezes, snowmen and Iron Golems. But the problem is I want them to spawn in the daytime or at night. I tried adjusting spawn weight and spawn types. The only one that spawns breezes in the daytime is the AMBIENT spawn type. Only problem, is that over 6000 of them spawned in less than 20 seconds. This is with the mob weight at 1. Another problem I have, is that instead of Iron Golems and Snowmen spawning, it keep spawning pigs in their place. I have no idea how to fix this and why this happens, but this is annoying.

If someone could give me a mob spawning procedure, I will greatly appreciate it.