@Nat093,
Nat093 wrote:
Which of the sentences is the most accurate? In other words, which one should I use when expressing my feelings towards someone?
1) I think about you all the time.
Simple present tense. A general, ongoing state, habit, routine or condition.
Quote:2) I'm thinking about you all the time.
Present continuous. Pretty much the same as 1)
Quote:3) I've been thinking about you all the time.
Present perfect continuous. Implies that what you have been doing in the past is affecting the present and may continue into the future.
Like Ragman says, any of them will do the job.