English Usage: Can't Help...

Usage : Can't help loving...

I always use the form: I can't help loving..., can't help thinking..., can't help falling...

But I often hear people say, "I can't help but love you." "I can't help but think of you."

So, I asked which form is correct?

Dictionary.com comes to the rescue:

Idioms & Phrases
can't help
Also, can't help but or  cannot but :  Be unable to do otherwise.
For example:

1. I can't help thinking that the keys will turn up eventually. 

1. He couldn't help but believe he would pass the entrance exam.

1. I cannot but applaud his efforts. 

The first of these phrases, can't help, is always followed by a present participle whereas the others take an infinitive. [c. 1700]