Would it work if i took 42 days of bc, then 7 placebo, then 42 days of bc again, then 7 placebo and then the regular 21 days of bc?

That should work: If you used continuous cycling birth control for three months for a few cycles and then switch to a traditional 21 day on - seven day off birth control cycle, you should be protected against pregnancy. It is always important to check with your provider if you are changing your medication.

Yes . . .: The typical 28 pill birth control pack consists of 21 active pills (full of hormone) and 7 placebo (sugar) pills. Taken as directed in the proper sequence, the 21 active pills protect against pregnancy while the 7 placebo pills allow you to have a regular period. However, this period is optional such that some birth control packs consist of 83 active pills & 7 placebo ones. Or do as you've done.