Why are you coming off HRT? Which HRT are you using? If you don't use enough progesterone, then an appropriate withdrawal bleed may not be triggered - this could result in a build up in the womb lining. Only reduce the oestrogen until you stop completely (maybe take oestrogen every other day?) - you may find the bleeds stop when your have greatly reduced the oestrogen.
Missing one pill per fortnight is not actually reducing the HRT. There is no real evidence that gradually reducing the dose will make any real difference but some women choose to reduce the daily dose of oestrogen over a few months in the hope the meno symptoms won't return too quickly. It sounds as though you are on a sequential HRT? If so, I really wouldn't reduce the progesterone phase - this might allow the womb lining to build. Reducing the oestrogen gradually would be the thing to do if you really want to. If you can get a lower dose HRT prescription from the GP to use for the next 3-6 months before stopping altogether, then this could be better.
If HRT is giving you quality of life - then why stop? Unless you are over 60 or have health issues that make you at higher risk when on HRT, then there really is no reason to stop HRt. It's about benefits versus side effects - the risks are very small. DG x