What's my best course of action now? Just repeat strikes until I hit 230 and then start doing Nightfall?
Doing (heroic) public events is the quicker way to level, but running strikes will get you the same thing, just a bit slower.
I would recommend trying to run the NF today as reset is tomorrow, so you'll get rewards today for completing your milestone & you'll get a whole new set of milestones tomorrow.
If you're trying to level as fast as possible, run heroic public events until you hit 260/265, THEN do your milestones. Milestone rewards will scale up with your level, while all other loot (aside from exotics) will drop a few levels below your PL once you get past 265. John has some great leveling guides in the OP if you're interested.
If you don't care about leveling as fast as possible, do what looks fun. You will have tons of opportunities to level up going forward, so don't stress or worry about what you're doing. Also, keep in mind you CANT mess anything up, so have fun.