Ask The Doctor: I’m getting some breakthrough bleeding while taking HRT. Is this normal or should I see my GP?

Question: Is breakthrough bleeding while on HRT normal? I have been using an oestrogen patch twice weekly with 14 days on progesterone for a few years and recently my periods have gone from regular to maybe every six weeks. However I do get breakthrough bleeding about a week or so before my period, both brown and bright red. Is this normal or something I should check out with my GP?