It must be love, love, love
Many people are afraid of being the first one in the relationship to say those words 'I LOVE YOU'. Timing can be difficult and normally, people are worried that the sentiment wont be reciprocated.
If you really love your girlfriend truthfully by your heart, then you really do not have to prove yourself by telling her so. Your actions will speak louder than your words. You do not have to do anything fancy for your girlfriend in order to prove that you love her a lot. You should do what you feel like. The feeling should come out of your heart and not from your mind. If your girlfriend loves you a lot too, she will appreciate your effort that you have put into it as you are very special to her as well. You also do not need to tell her every few minutes how much you love her. Even if you just say it once a day, it would be more than enough.
How to prove to your girlfriend that you love her
If you truly love her a lot tell her, tell her everyday how much you love her, take her out to eat on random days, and buy her flowers every now and then, and tell her thank you for the things that she does for you. Just be yourself and let your emotions take over, be nice and sweet to her, do sweet things for her and remember to always let her know that your always going to be there for her and that you will always love her no matter what.
You could also give her a gift that is really thoughtful. Present it to her on a Tuesday or some other random day. This should be something from your heart. Tell her that you love her care about her a lot. She will see that you were thinking about her and know that you are sincere. Take the leap
Take the risk
without taking the risk and telling someone that you love them, you may risk losing them if they do not feel that there is commitment from you, and you could end up regretting keeping your feelings to yourself. Who wants to go through life wondering 'what if'? Take a risk and be honest about your feelings. If you lose someone because you open up to them and tell them that you love them, then as sad as you may feel, you will have to be content with knowing that they obviously weren't 'the one'.