10 points for best answer...really need loads off answers pregnancy!?

if you definately ovulate on day 18 then your period begins on day 23 then it will be difficult to get pregnant as you will have a luteal phase of 5 days and it isnt long enough, to concieve it needs to be at least 10-12+. you should speak to your doctor there are ways to lengthen the luteal phase and make it easier to concieve, but this is why you are finding it a struggle to fall pregnant because by the time you ovulate your period flushes the egg and sperm out when they are getting ready to implant. you will get pregnant but probably not without help. good luck.