You know, I just had a version of this discussion on another site, and I got lambasted for giving the advice to fight back. A woman who is a rape crisis counsellor said that lots of attackers like the struggle! Who knew? I guess every situation is different. You will have to judge your attacker if it happens.
Anyway . . .
If you have keys, carry them in your fist with a big one sticking out from between your fingers. Also, a big metal keychain is good to swing - mine has a mountain climbing hook on it, weighs a ton, good for brass knuckles. oops, those are illegal, sorry.
Remember that a woman's strength is in her lower body - and so is a man's vulnerability. Kick and kick and kick again.
A friend of mine who used to teach karate told me that, if you can get two fingers up someone's nostrils, their head will always follow their nose. So noses make a good handle - as in, he has you against a brick wall and you manage to smash his forehead into it.
I don't know about pepper spray - that's illegal in some places too - but a good old air horn is useful. We used to have one as a distress signal when my parents had a boat, so you can imagine it is quite loud. Close to someone's ear, it should at least stun him if not actually blow out an eardrum. And since it doesn't sound like a car alarm, people are pretty likely to at least look.
Hey, let a few of your neighbors know. If he can't get to you at work, he might try to find you at home. Not to scare you, but so you can be prepared.
What an amazing boss you have! There's someone who cares about his employees more than about making the sale. Good for you for speaking up.