Am i [20F] expecting too much of my [20M] boyfriend of 2 years?

Honestly I know i have slight problem with expecting too much sometimes, I think that because of my situation as someone who is currently not full time employed i don’t fully understand the situation he’s in as a full time employee sometimes. That being said normally i don’t really mind and i have learned to deal with it and not really be annoyed or upset about it anymore so i would I’m doing better?? Recently though I had a bit of a health scare there might be something wrong with me physically and it honestly really scared me, i explained this to him and also that i would have to have follow-up appointments concerning it. It isn’t something i’m blowing out of proportion i don’t really want to say too much but it could be something as serious as cancer so i would say personally i have a right to be scared.

This being established, 6 months ago I had my first appointment concerning it and i went alone, worst experience i’ve ever gone through i was terrified, scared, alone, sad, and idek just about a billion emotions going through me and i was just so scared and afraid and felt so alone going through this by myself. I explained this all to him, how scared i was how alone i felt and overall how bad it was for me and he PROMISED and i’m emphasizing this because he took it upon himself to promise me, not me ask of him or make him promise, but he chose to promise me that he would come with me to my next appointment.

Now it’s time for my follow up appointment. He has a very set schedule he knows what days he’s scheduled for and almost always has the same schedule and he’a known for a while that he would almost 100% be scheduled for the day of my appointment. The weekend before it he takes off Sunday knowing he has a party for his mom on Saturday, i have no problem with this because why would i but now it’s about time for my appointment and just 2 days before he starts telling me “oh i’ve been wanting to find somebody to switch with but i can’t seem to figure it out”. I know he had a chance to switch it out a while ago or call off if he really wanted too but he CHOSE not too and it’s really getting to me, i didn’t ask him to come with he again CHOSE to promise me and he CHOSE to not prioritize me over getting drunk this past weekend. I’m honestly just upset and disappointed because he knew how scared i was how vulnerable this whole health situation is making me and i’ve been with him through a lot of personal issues choosing him over myself sometimes and i only expected maybe he keep his promise about something like this? Am i overreacting?

TLDR: Am i asking too much of my boyfriend by being upset he didn’t prioritize my health over his job?