I understand how you feel, my mother is in poor health but I find talking to her on video call or phone to be far more reassuring than text. Often when someone says they're doing fine on text it sounds like they just don't want to talk about their health but on video you can see how the deliver that sentence and get a feel for their mood. Turns out my mom just liked to grumble sometimes about her aches and pains but actually is quite upbeat and this helps me to stop worrying about her.
Ive also planned to isolate for 2 weeks and get a private covid test in order to safely see her at Christmas (if home mixing is allowed). This means I can stop worrying about making the most of the time with her, I find making plans, no matter how far away or simple helps me to feel I'm making the most of her while she is around. Sometimes we sit on benches in the graveyard (less people around) and talk from a long distance wearing masks, just to feel like we are in each others presence.
I hope you can find some peace with it and enjoy some video calls or socially distanced walks with her in the future 