Nervous about Marriage

Salam,
i grew up in a very traditional Pakistani family and 2 years ago I got engaged to the daughter of one of my relatives, I had no issue because I had no girlfriend and never had any kind of romantic relationship and also I was raised very traditional ways. My fiancé is also a very amazing person, she is smart, intelligent and beautiful. She is studying at a medical school. I sometimes feel as though she deserves better than me and it's causing a lot of anxiety. I am flinking in university and I don't know where my future lies. Due to all of this I fear that I will not be able to fulfill my duties as a husband and I think she deserves someone who is of her level, someone that also has the qualities she does.

Am I selling myself short?
Is this normal?

How closely related are you?

This may be a big problem for your future children as the chance of birth defects is drastically increased with close inbreeding.

Thank you for the response.

I am also currently studying pre-Med. I don't have failing grades anymore, maybe flunking wasn't the right word to use. I struggled in the first two years of college because I was going through an unstable environment at home involving my family. But thanks to almighty Allah I overcame that and have been doing well recently in school but the hole that I dug for myself in the first two years is making it difficult to be competitive for medical school entry.

Marriage is a contract between two consenting adults of sound mind...