@SoundisPlatinum = +2 proficiency bonus is correct for levels 1-4, at level 5 it becomes +3....5E D&D rescaled things a lot from earlier editions.
Have a look at https://www.5esrd.com/classes/fighter/
Of course, I'm not sure how closely the rules are being followed (see numerous threads
Not sure how they compute XP - but in the 5E SRD it's 700 XP ;-) (divided by 4 I assume) ... I guess you'd level too quickly if they used the actual tables?