Doubts are often a normal part of getting married.
On my second marriage, I made my decision differently than the basis for my first choice. I thought about our disagreements, arguments, and bad times in our time together. I decided that, if I could take him at his worst, I could take him at his best. When you're together and snuggling, it's not a time to say "ah yes, this is why we should marry".
Many divorces are people who truly loved each other, but couldn't live together because they didn't handle disagreements and arguments constructively together. Some people you can love, but have to show your love by not living with them.
So... what you didn't include here is what you need to look at.
When chosing things to do, including the wedding... did you agree on everything? If not, look at the disagreements! How were they handled? If he's right for you, he would disagree with you withOUT name calling, insulting, putting you down.
Don't feel guilty about you having doubts and his not having doubts. Feelings are just indicators of how we're handling the stress in our lives. They are not right or wrong. It's not our feelings that's important... it's how we deal with them, and with the stressful times in our lives that's important. Feeling guilty is a waste of your energy... it's a way to make things fail! Accepting your feelings of discomfort is valid. Feeling guilty is NOT valid.
So, sit down by yourself and review the stressful times you two have had. How did YOU treat HIM in those times? How did HE treat YOU in those times. That's what tells you if you're both ready for commitment required to make a long-lasting marriage.