Two questions.
My family insist on using Whatsapp for the family chats. I have to keep a copy on a device just so I can communicate with them. I do so under protest, as I was always told it isn't secure. My brother has just said
"oh Whatsapp is encrypted, it's perfectly secure".
First, is it actually as encrypted and safe as my brother claims? That would solve everything.
Second, if it isn't, where can I get some proof that we should switch to Telegram or whatever? Proof which doesn't make me look like a raving loony?
In a similar situation as you (entire society revolves around whatsapp). I came to this conclusion:
Others won't share my view on personal privacy at all will happily give out any metadata or data. No matter what secure channel we use, the destination (people) will always leak.
Because of (1), consider all communication with others as public, no matter the inferred intimacy, no matter the platform or its security.
Consider (2) as true even if they somehow used Signal or any secure platform, because of (1). (E.g. "Hey, did you hear about $familyMember? Yes, the weird kiddo who forced me to use some strange blue shit for chat. He got positive on blood exam for $badCondition. Go check on him")
As for whatsapp itself, i use Android and isolate it in a separate profile, also frozen until opened. I also used a burner phone number for account registration, not my actual number.
People are more receptive of whatsapp accounts with "alternate" numbers when you explain you "got hacked in the past" or any plausible reason.