AIW for feeling frustrated with a co-worker's ongoing absence

Apparently, AITA doesn't allow posts if there's no action taking place to judge, so I thought I would try here.

So my co-worker, let's call her Karolina, has been absent from work since late February. She had been signed off on a doctor's note twice for March and April, and every time it comes to the end of the time period , she's called in to say she won't be coming in when she said she would.

Now this isn't the first time Karolina been off sick, she does have health problems that haven't been specified by our supervisor nor herself (which is fair, we're not entitled to her health problems), but this has been the longest she's been away from work.

We're a team of 7 people at the moment within a big corporate international company, and my supervisor is currently looking for another member to join our team. The way our team is set is we have the supervisor overlooking the entire team (let's call her Abby), we have a senior member recently promoted who looks after a huge account, and there's a buddy group of what should be 3 people in each group. The 3 we have at the moment are in their buddy group, mine is with Karolina and an open position for another.

So Abby and I have been covering Karolina's work since her absence, but my supervisor has also got higher responsibilities to manage herself, along with training a new member who joined just only a month ago, and currently she's away on annual leave.

The senior member (let's call him Mace) is currently covering Abby's position until she comes back next week, and Karolina was due back this week. Well, she called in both Tuesday and Wednesday to tell us she's not coming in, and she was trying to get another doctor's note.

At this point, I can tell that there may be a possibility of Karolina being let go because of this, but looking up on sickness laws here in the UK, she is still protected until the three month mark of being absent from work.

Abby was telling me last week that Karolina will definitely be back by this week, but Mace was on the same page as me in feeling unsure this was going to happen. Mace has been keeping me posted on the fact that Karolina will not be back this week, and I can tell he wants to say something, but whatever he wants to say out loud he knows won't end well if it comes out. He did say they can support me if the work load gets too much, but between training the new starter and having to look after our own heavy workflow, it'll be difficult to do so.

So now we're left in the dark about the whole situation, and it's leaving me with managing both Karolina's work load as well as my own with no end in sight of when she would come back, if ever

I understand that whatever she's been signed off for must have been horrible, and that she should be allowed privacy on her condition, but now it seems my patience as well as the rest of the team is running out.

So am I wrong for feeling annoyed with my co-worker's absence? The reason I feel wrong is because of the following:

1. As someone who lives with a person with a chronic illness that had to be signed off for recovery, I feel like a hypocrite to be irritated at this co-worker whilst understanding for another.

2. I was signed off myself during the Christmas period from a bad cold case which led to my eardrum bursting with an infection. I was virtually off for three weeks during this time and came back in January.

3. I understand that it should be the higher ups' responsibility to bring in another team member so I can get the support and eventual cover for when I will be away on annual leave in June (Abby has reassured me that they will need to handle all of this and to not worry myself about it).