Help! Question on the pill?

So i recently got switched to Blisovi 24 from Blisovi 1/20. They have the exact same active pill, but Blisovi 24 has 4 placebo pills, and Blisovi 1/20 has 7. In order to keep my period schedules the same, I skipped the last 3 active pills in the Blisovi 24 pack so it would be like the Blisovi 1/20 with a 7 day placebo. Is this okay? Does this create a greater risk of pregnancy? From what I remember, my doctor said it was okay, but I really need reassurance.