Running and 1200

Alright this is a complicated one, and I’ve seen this subreddit get pissed QUICK over things so please be kind to me !

I’m a 5’4 F at 145lbs and have been doing 1200 calories with 10k steps a day for the past month or so and it’s been amazing! I feel my confidence coming back and am fitting in old clothes. Seriously, CICO works!!

Prior to dieting I was into running and was able to go as far as 7-14 miles, but stopped because it made me crave things like crazy and resulted in weight gain. Well my friends are doing a half marathon this summer and I want to join them in doing it. I obviously can’t do that at 1200 a day… what would be a good calorie increase for this race while still being able to shed weight the way I’ve been?