I am pretty sure this is just because of your starting and changing pills and that can definitely effect your hormones that control your period. The only thing I think you would have to worry about is if the time between ovulation and your period were less than 10-12 days when it should be 14 days. I think that as you take the pill your periods should be more regular and start on day 1 or 2 of the sugar pills. Hope this helps =)
The length of your period is a non-issue. It can be as short as 2 days and is not indicative of a problem.
thanks for your comments, i was hoping it was just my body adjusting to the new pill and hormones, so your thoughts are reassuring. I think i will wait another month and see what happends and then maybe take an ovulation test to see if i am ovulating through my cycle to check all is working well. Although i am not sure whether you are supposed to ovulate while on the pill and they are only suppposed to be false periods - any ideas.
as long as there are at least 10 days after you ovulate before you get your period (for implantation), you should be fine.