Hello,
I have a 20-30 day cycle and O around cd 18-20 giving me an LP of 10 days. Initially I was quite anxious about this but after doing some research there are a few things you can use to extend your LP. The most obvious one is Vitamin B6. Lots of ladies find this really successful, some saying it can extend LP by several days which is really encouraging.
I started it this month, around cd6 as I was still researching it and was undecided, and I O'd on cd 16! Not sure if this is a coincidence but there it is. If my LP stays at 10 days, then AF will arrive in 2 days time, but if she arrives closer to the end of the week than I will be very happy (even happier if she doesn't come at all)
If this doesn't work, progesterone cream is supposed to be fab, but it depends where in the world you are as to how easy it is to come by! If like myself you are in the UK, it will need to be prescribed by a GP.
If you google short LP, or LP defect, vitamin B6, lots and lots of info will come up. Also if you go to the search bar on this site and type it in, posts about it from the last few years will come up and you will get the benefit of other ladies' experience. Also check out other TTC sites where ther is an abundance of info!
It seems to be quite a common issue, and one that in many instances can be sorted out quite easily with VB6. Have a read around the issues and see its for you. If it is start low at 50mg, and increase it as necessary as some people have found too high a dose can make their LP too long! (not above 200mg though).
I will let you know how I get on towards the end of the week.
Good luck!