Almost never initiates plans and (possibly) forgot my birthday – friendship red flag?

So basically I regarded my friend/coworker [30F] and I [25F] as a pretty close friend of mine, and assumed I was the same for her. We’ve been hanging out outside of work for the past 8 or so months almost every weekend and are good work buddies as well. We are also both each other’s only close friend right now, as far as I know. However, we now only see each other once a week at work, so most of the time we see each other is when we hang out on weekends. We also usually make plans at the end of our work day, because she usually goes off the map and turns off her phone during the weekend.

Anyways I am usually the one who makes/initiates plans to hang out. She is a shy person, so I get she might not like initiating. She also nearly always accepts and we have a good time together so it’s not a big deal, but last week, I asked her like usual to hang out and she declined, saying she was busy. She said that the next week would be better for her, though. I understood, but I figured I’d leave the ball in her court this week since I asked last week.

Well, my birthday is this weekend, and I know she knows my specific birthday because the past few months she would make vague references to it and has never gotten the date wrong. I also got her a nice dinner for her 30th birthday a few months ago so I (optimistically) thought she might return the favor. She kept saying things like “oh I’ll have to get you ___ for your birthday since it’s coming up,” “we’ll have to do something on that Friday the 8th before your birthday since we work together that day,” things like that.

Anyways, today at work she kept saying how she was busy/tired, so I didn’t want to push hanging out on her again especially since she declined last week, but I thought she might step up to the plate and offer to do something for my birthday. Whether it was give me a gift, make plans, anything. Even without the whole birthday thing I thought she might suggest hanging out in general since she canceled last week. She is however taking care of my cat this Thursday (which would be several days after my birthday) since I’ll be leaving for a trip, so I thought maybe since I’ll be seeing her then, maybe that’s why she didn’t suggest another day to hang out.

But no, when we were leaving work she just awkwardly kinda followed me on my way home (a longer route for her) and didn’t mention anything (maybe she was waiting for me to ask her to hang out like usual?). At the end I said, “OK I’ll see you on Thursday then?” and she just had this confused look and said “Thursday??” and I just said “for the cat” and she was just like “Oh yeah. Okay bye” and that was that. So she barely even remembered taking care of the cat even though we had just discussed it that morning and I had given her a month’s head’s up.

Does this seem like a friendship red flag (me initiating 75% of the time/her not seeming to remember my birthday)? Or just that she maybe doesn’t see me as close of a friend as I consider her? Or just a bit scatterbrained (lol)?