This is a lesbian's worst nightmare. Sorry you have to deal with this. Reporting it as a stalker sounds like it might well be the best step to take as others have suggested.

I mean I'm 5'2" and physically I'm no way his match, and I feel really intimidated because I know I couldn't defend myself if he actually tried something

Don't underestimate yourself. In a fight, a lot of abusers expect to be the ones with the power, and are actually cowards the moment you show you won't let him fuck around with you and that you're willing to fight back. By showing you're not scared, you give yourself a mental advantage over him. Self defense classes are also a great idea.

Do you enjoy knitting? I would suggest faking taking up the hobby and carrying around some yarn and some long, sharp needles. A long sturdy needle in each hand makes an effective deterrent if he attacks you physically. If he really wants to touch, make it clear from that point you'll make it cost him. Spikes of that nature have a long history as a discreet but effective self-defense tool for women from ladies' hatpins to Chinese emeici, that doesn't require a lot of raw physical strength to inflict a lot of pain or damage like a club would be. Pepper spray requires hitting one specific point, the face, whereas a needle in the arm, leg, or hand will be very effective as a chance to escape, and pepper spray can accidentally be blown back into your face by the wind, etc, and carrying around your knitting is something that lets you discreetly carry something for self-defense whereas you likely run into legal issues with pepper spray or a proper knife. The needles can also be thrown if need be. In order to cover yourself legally, do not admit to anyone the reason you're carrying them; as far as anyone knows and if anyone asks, you're now very fond of knitting.

Obviously, protect yourself legally by not resorting to anything physical or even showing you have a weapon unless you're in danger (he corners you alone in an alley, he puts his hands on you, he has a weapon).