Most Helpful Girl
Show they how highly you value them through your actions. I wouldn't put too much importance on just telling them I love you.. actions speak louder than words. It's through the little things, like going out of your way to help them or just make them feel looked after that speak much louder.
For example, because giving anecdotal evidence is my thing, I've been with my boyfriend for 2 years. Neither of us have said 'I love you' but I do love him, and I know he feels the same about me without a doubt. How? Just the way he looks at me sometimes, whether he took me out for dinner or we're studying while face-timing then I'll look at the screen, and he's looking at me all googly-eyed. Or if we're playing badminton at the 2 hour sessions at the gym and he'll spend over an hour helping me perfect my serving technique.
Things like that are way more indicative of whether someone loves you or how much than buying expensive gifts/dinners. :)0