It's perfectly safe and perfectly okay to skip a period on the pill. You're right, it's harder on triphasic pills, but since you're on monophasic, you should be fine. If you've only JUST started on the pill you have more risk of breakthrough bleeding, but if you've been on the pill for several months already or more, you should be fine. Just take all the 21 pills of pack one, throw out the placebos and take a new pack. At the end of pack two you can have a period or skip again, although the more months you skip, the higher your risk of breakthrough bleeding. Don't worry about lining "building up" inside you, because while on the pill not much builds up anyhow, so it isnt as though it will just keep building and building inside you. Your next period might be slightly heavier, but most likely will be exactly as it always is.
Good luck!