Congratulations!! You lucky thing being 12 weeks you have fast forwarded and won't have to wait so long!! Don't stress about what you did/didn't take before you knew, when I was pg with DD1 we didn't even know about folic acid! (she is fine by the way LOL) I took Blackmores, as advised by others here, throughout my last pg and beyond, Coles has it as do chemists and healthfood stores.
Good luck with the rest of your pg you will find so much support and friendship here, you'll love it.