Hi Amy,
There are many things you can do to ensure you have sex at the right times of the month, but this does add a lot of pressure. Many say that best way to do it is to have unproctected sex whenever you feel like it.
The other ways are:-
Ovulation kits:- These urine tests give you and indication of when you are ovulating. They should be used from day 10 of your cycle onwards. These needs to be taken in the afternoon, you can't have drunk too much liquid as this makes it harder to get a result and you can't wee for 4 hours before hand.
Cervical Mucus (Sorry!!):- During your cycle your cervix is filled with a mucus plug, when you are approaching ovulation this thins out and goes to the consistency of egg white (Sorry Again!!!) this enable the sperm to travel better to the egg
Taking your temperature:- You need to take your temperature every day before you get out of bed, had a cup of coffee etc. When you are approaching ovulation your temperature will drop then you will have a higher serge, this ususally indicates you will ovulation within the next 48-72 hours.
As you see this is a lot of faffing about. Your best bet is to try for 6 moths just having sex when you feel like it. If you have had no luck after 6 months then try this but as I said this does add pressure and can make it feel a bit military!!! Remember if you have been on the pill or had the injection it can take a while to get pregnant afterwards and for your periods to return to normal. It took me 9 months the first time.
Good Luck
Love
Kate