My husband and I have a 2yr old and have been trying to get pregnant again for a little over a year with no luck my periods are not regular I may not have one for 2 or 3 months and when I do they last for 16 to 20 days sometimes longer What should I do to get pregnant?

Since you have been trying for a little over a year, and your cycles are not regular, you may want to consider seeing your doctor for a check-up.
They may suggest sometime to see if your periods can't be made more regular, they may suggest some initial fertility testing for both you and your husband, they may say just give it a bit more time.
Even though you have one child, it can happen that you may experience what is known as secondary infertility and a little help may be all it takes.