I had a similar situation to you Elly, my husbands family was all boys, so i bought the shettles method book, and we tried it and we got our girl!! now we will never know if it was just sheer coincidence or the method but it worked in our favour, they say that you BD up until about 2-3 before you O and then stop as the girl are not as fast a swimmers as the boy but they are more plumper and live longer and can live long enough to reach the egg when its released, but the boys are faster swimmers but die alot quicker, so they generally all are dead by the time the egg has been released!

hope this helps you out!

Shellstar76