Have I been hacked?

I think my neighbour has possibly hacked my phone. I’ve had all the signs, battery drained, phone gets hot & is really slow, strange noises on calls, screen lights up for no reason etc. I recently learned she had a key for my house & has been running her devices from my WiFi. I didn’t set this phone up for sometime, it was left in my house for a few months before I used it so she could have done something then. I’ve tried the *# code and no calls were being forwarded etc. But I’m certain she’s accessing at least my social media’s, imessages & WhatsApp. I was wondering if the following things could be signs of either spyware or cloning. Or if anyone can help?

1. instagram app on settings show a “version” & “branch” no other apps do & I’ve had logins that weren’t me.
2. Finding apps contacting “firebase” domain a lot
3. when trying to call someone back via WhatsApp from my phone call log it has shown the number is “6262” or says number not available on WhatsApp?
4. App Store seems to be showing apps that show Chinese writing as the creators (not sure if this is unusual I’ve just never noticed that before). I have checked for Cydia & it doesn’t seem to be on my phone.

im not very tech savvy so apologies if any of this doesn’t make sense. I appreciate it sounds a bit crazy, but this woman is OBSESSED with me. Shes stolen things & damaged my cars so many times. When she had WiFi access she would regularly pause and unpause my devices… she’s a very odd woman who I’m sure would get a kick out of accessing my private messages/accounts. Any help would be greatly appreciated. Thank you