I’m probably not going to be a huge amount of help, but didn’t want to read and walk away.
I have two DD’s; oldest nearly 4 and youngest 18 months. Oldest DD (from recollection) seemed to be right on track for her speech milestones. My 18 month old seems a way behind in terms of speech. We have babbling, a couple of words and sounds for certain things (eg ‘Nia’ means snack’.
I am a worrier when it comes to development, and spoke to my HV a couple of weeks ago. She took me through some questions geared towards more general development, as well as those specific to comprehension and communication (does she point to something when she wants it, does she understand when you say you are going to put shoes on, etc). The HV felt that she was on track, but perhaps just focusing on developing her skills in other areas (her fine motor skills are better than my older DD’s was at that age, etc).
Don’t punish yourself for not being able to work on this over the Christmas period. There is very little you can do about it if you are ill, and you should give yourself credit for being able to meet basic care needs and provide stimulation. Not being able to focus on developing her speech over the break is not going to have any sort of lasting impact; consistency and regularity is far more important, so try just to make sure that you carve out a period of time every day to focus on it.
You are doing the right thing by liaising with your HV and getting their advice.
As someone who spends much of her time berating herself for not spending enough time with the children, doing enough activities, supporting their development, etc, I can see the hallmarks in someone else!
Try not to worry yourself too much - different things take different times with different children - knowing the relevant milestones is helpful, but remember that they are only guidelines!