[mesmark]

general rule is

2 syllables or more: more/most
2 syllables but the last syllable ends in y: er/est
- hungrier
- sleepier
- angrier
- heavier

I tend to pronounce cuddly with three syllables [cu-di-ly] so for me it also sounds a little wierd, but say it (correctly) as two sylables, then it's not so bad.

I hope that helps.