I want to celebrate 1 year anniversary of my relationship
Is your anniversary coming up?  What do you want to do to celebrate?
I want to have more special dinners with my girlfriend.
If you want to celebrate your anniversary it's cool. Go for it. Your gf will appreciate it.
I feel a bit undecided about it, as if other people might say I shouldn't, but I'll do it anyways.
I don't know why anyone would advise you against celebrating an anniversary, so I say you should plan a special dinner.  Make the arrangements, but let your girlfriend know in advance, just in case she isn't aware of the date's significance, and I'm sure everything will go great.