The age thing - oh and btw the OP's BF is 26 not 22 - is something that I have always balked at. I didn't marry very young and was glad that I took my time to look around. However, my eldest son has been married almost a year now, and he was 23 and she 20 when they married. They met in high school, and other than a few glitches, they've been together ever since. Therefore, although they've only been married a year, they've been together for much longer. I see in them a lot of immaturity, even at this point, and I wasn't incredibly happy at first when they said they were getting married, but I hope and pray it will work out for them. I believe that they are determined to stay together and make their marriage work, and that matters. They both talk long term, "in 5 years" "in 10 years" and both have agreed they are not ready for children yet (which is good.) OTOH, one of my other sons recently broke up with a GF of almost 3 years, despite them both discussing marriage as a near certainty. He has determined that it is too soon to be talking about marriage (they are both 19). My husband and I are both very disappointed that they broke up, but also understand that it has to be right for my son, as well as for the girl he marries. It was perhaps too good to be true that the both guys found the ideal girl so early in life, and that it was their first real girlfriend. So, he isn't dating now, and I have told him that he probably shouldn't for a while, because he is still in college and has a long period of study ahead through to doctorate level.
I think that's where I really would draw the line when it comes to waiting for this guy. College is a time for study, and for learning about the world also. College students need to wait to marry until they have graduated - preferably with a good GPA. That is far more important at this age than marriage or engagement. I'm glad that my eldest kid held off getting engaged until he had graduated and actually had started a job, and had an income. My biggest concern about my other kid who was seriously dating was that they didn't get married now, while both are at college, as they wouldn't have any way to support themselves. Sure, as parents we help, but like most parents we have other kids to raise and support through college. When our older kids are getting married, we hope that they are able to start out in their own home and with their own lives, to relieve some of the financial burden from our shoulders.
So, while I understand the OP's concerns, I would really wait until after graduation and see what happens. If he still continues to talk engagement/marriage and not do anything concrete, then he probably never will. Then it would be time cut the losses and move on.