It's common.
You love him so he's a big part of your life.
You have worries and doubts as a subconscious mechanism wanting to be the best person you can be for him and yourself. It is your way of trying to better yourself to better your own life and his.
But it does no good living in the past or dwelling on the future so much, that is unhealthy because past and future are "out of time".
The solution is to try and live in the present, and just enjoy NOW for the time being.

You're trying to tell yourself your love isn't good enough for him, and maybe it isn't. Is any one of us "good enough" for our better half?
Just relax. You think too much.
Try and realize that intellectualizing emotions is a futile effort. The feelings in our hearts is something much bigger and grander than the mind can ever facilitate.

Remind yourself how lucky you are to be able to share time with your YF.
He's an amazing gift that you deserve otherwise God wouldn't have put him in your life. Accept the gift. Realize how fortunate you are.
Count your blessings.
Don't let petty fears intrude upon the peace & joy to be had building memories together with your friend. Even if they're not the best memories, it's better than no memories at all.
You'll be okay marc, you're fine, everything's alright.
Same thing happens to me whenever I fall in love too so I know how you feel. Good luck to ya!