I just can't seem to say "I love you"

Don't force it. You'll tell him when you are comfortable with it. You don't need to say it just because he says it. Let it come naturally to you, then it will feel good to say it.

Start out by telling him you enjoy his company (if you really do that is) and that you are glad to know him. That will help you validate that he is treating you right, but let you take your time with making sure you're ready to say "I Love You".

When you really feel like you love him, it will just flow naturally from you. Until you feel like you do love him, don't even try to say it. Even if you did, it wouldn't mean anything if the feeling is not behind it.

Do you really love him? Because if you don't then I wouldn't recommend saying it until you do.

It doesn't matter what your friends think it only matters what you think. If you are having trouble saying "I love you" then you're not ready to say it yet. When the time is right it will come out naturally so I wouldn't worry about it and don't try and force it or you'll sound insincere.

Don't think about what others think..
And maybe your just not ready to say the 3 words yet and that's fine because if you say it and don't mean it or just to make him feel better then its not healthy for your relationship..Just wait for the right time to say it..If he says it just look at him in the eye then kiss him ..that will do....

When you love him you tell him, no sooner and no later.

Don't even think about what your friends are telling you this is your relationship and you'll tell him that you love him when your ready. When your ready it'll be natural don't try to force it'll come.