hopefully my last question regarding my PIP review

hello again,
I have virtually finished filling my review, just a few odds and sods to get done, the main one being trying to get a letter of support from my doctor, I have for the first time got a letter of support from my younger sister, as she knows me, and she is a experienced registered nurse, and a letter from my elder sister, who has basically become my main carer, in the past I only sent doctors notes, now with my last assessment being in 2016, i have a letter of support from my doctor from January 2019, so it must have been sent with my application for ESA, i am due to speak to my doctor tomorrow hopefully, haven't had the usual text from GP surgery reminding me of telephone appointment, which is unusual, my doctor has been off sick, I think he is back but not sure, since covid, my appointments with my doctor have all been over the phone, and i have noticed, he shuts the appointment down quicker than when we used to have a face to face, so my question is, if my doctor cannot do a letter of support for me, should i send the 2019 letter, although, certain conditions have got worse, or just send the letters from my sisters? i am tied down by time constraints in getting my new support letter, if he agrees to do one, it would have to be done pretty sharpish, or he may say he does not have the time this time around, and when I get my ESA application review, don't know when it is, but it can't be too far away, I would assume, I will need another letter of support from my doctor, he has never said no to a support letter before, but we are now living in days of covid, and everything has changed, they are under far more pressure, and seem to have less time to help out, any opinions welcome,
thanks in advance