Anxious cat - help?

[KatyMac]

OK we are the third owners (I think) and she was born Dec 2019 we have had her since midMarch

We have extra strong feliway & she is predominantly an indoor cat - a catio is a possibility

She isn't very happy; she stalks and attacks our feet, she over eats, she is very bite-y - we just had to change her food which made things worse

She isn't play fighting really although she does occasionally - it seems real more of the time

She just gives off stress vibes - I was concerned and a friend visited who said I was being ridiculous and by the time she left the friend agreed she was stressed

Any suggestion of techniques to make her feel happier

Found my neighbours cat peering under a car when walking to the shop earlier. My fella underneath it. Was crouching down and a different neighbour came out asking if it was my cat.

He has been hanging around their garden with his cute little face. They fed him ham and bought cat food for him.

Is it a territorial thing that he doesn't like anyone else in this house? He doesn't get too close to neighbours. Eyeballs them through the window looking for food.

I might have to go around and put notes in their doors to tell him he is not a stray.

@KatyMac

I know she is a pretty little thing and I feel so bad we are not helping her more

I will get some in the next day or so

You are giving her a lovely home, food and proper vet care. A much better life than she had before.

Only a few days in and she is much less anxious, less bite-y and the oddest thing, her fur looks better, softer slightly more fluffy and better groomed

Nope she is still very upset :(