I miss 1 birth control pill in week 1 & the next day I took 2 pills, then in week 2 I miss a pill again & took 2 pills, do I need Plan B if I had sex?

You might not have 2. But if you want to be extra cautious this would be a good thing to do. Forgetting two pills in a pack in theory makes enough of a drop in efficacy that you might want to have a back up plan. You could also use barrier methods (condoms) for the rest of this cycle as an added safety measure.
Probably not. But it cannot hurt to take a morning after pill. There is a very low chance of pregnancy with no missed pills, but with every missed pill the chances go up a little bit. Better safe than sorry.

Related Questions

I am on the birth control pill but missed one in my first week. I might have had unprotected sex....Do I need to take plan b?

Yes. In the setting of missed pills, the chance of pregnancy is probably slightly increased. If it has been less than 72 hours since unprotected intercourse, then taking planb would probably not be a bad idea. Talk to your doctor as well. Read more...