Try to communicate your feelings and emotions. You do not have to open up to her right away but gradually you need to show her how you really feel, an honest communication is everything for your woman.
You probably think you have more than enough affection but here are a few tips for you. Affection is the main way to show love to your girl, so don’t forget to:
Find time for your girlfriend, even if you are busy. Offer her to have a lunch together and even if you cannot see her because you’re swarmed with work make a quick call to tell her that you care. Do not ever let her think that you have forgotten about her.
When on a date with your girlfriend find a moment to cuddle up to her, give her a quick kiss or brush her hair.
Be a gentleman; do not hesitate to offer your help even if you think she will handle by herself. Take care of your woman; offer to help her with the chores, broken car etc.
Compliment your girl. But remember that your admiration and your compliments should be genuine. She needs to actually feel beautiful. If you cannot come up with a good compliment, check out the online articles about it. You will find plenty of ideas.