I was always told if you have an irregular period it can cause problems when you try to conceive is this true?

Depends: Irregular and missed periods happen due to irregular or missed ovulations. By definition you have mild ovulatory dysfunction, the most frequent female fertility problem (30%.) if this is the only abnormality you and your partner have, you may not even have problems conceiving. If there are other problems, depending what they are, your chances could be less good.