differences of seldom, rarely , merely

I used to use the word ' seldom' for ' not often ' a lot , but I recently found that native speakers ' seldom' use this word . Maybe they use ' rarely' more often . Which one do u prefer ? And for merely , I don't often see it either .

I guess SELDOM is mostly often used in writing, while they like to use RARELY in conversation. As to MERELY, true, I rarely see that either, only very occasionally.

merely means only

 ex: i was merely asking..

i agree with you..(merely) is barely used,,