Is it normal for her to bite so much?

Hello everyone. We have a seven month old female spayed Pekingese and a six year old Japanese chin. Hiroshi our Japanese chin was never really a biter from what I can remember but we cannot for the life of us get Nori (the Pekingese) to stop. I have new bruises and cuts every week, possibly every day. I will provide context on her daily life and what we are doing to try and stop her.

She gets up a 4 am to pee and goes back to bed. She gets up at 6 to eat and goes back to bed. She then gets up for the day at around 7-8 and plays/wanders around the apartment with supervision until maybe around 10 with potty breaks of course. I will put her in her crate or playpen for a nap as I work from home and the nap is usually about an hour or two. Maybe bring her out to play again around 11:30 or 12. Out for an hour or so depending on her mood and back into the playpen or crate for another nap. We pretty much do this throughout the day. An hour or so of play and about two hours for a nap.

She’s very sweet and cuddly. Loves to jump in my lap when she’s playing with her brother, kisses you in the morning and always wants belly rubs. ALWAYS. So so excited when you come home.

However she gets SO vicious out of nowhere. We’ll be holding her and suddenly she’s growling and biting. We yelp very loudly every time and disengage. We do not punish her, we only reward for good behavior. When she bites during play, we yelp and completely leave the room or get up off the floor and disengage for a minute or more depending on the severity of the bite. I’m thinking this might be normal from what others have said but I’m really not certain. Is this just the terrible puppy age where they’re still bitey and if we keep doing what we’re doing she’ll get better? I will say I feel like she is getting a bit softer sometimes when she plays and bites but we are trying to stay consistent.

One other thing to note is she does have an issue with food aggression/resource guarding. When we got her she would snap at us if we got close to her when setting her food bowl down so I started consistently petting her when I set it down, telling her she’s a good girl, and then occasionally rolling treats to her. I had to roll them otherwise she would bite. This has also improved because she will eat a treat out of my hand now so it’s getting better, but if she picks up sticks, mulch, leaves, anything unfortunate laying on the floor. Goodbye fingers. We have tried drop it and do say it consistently and at first she would listen and now she refuses and when we say drop it, she just eats it. I’m at my wits end with this girl. Thank you for sticking around! Any help appreciated!