Hi there and welcome. Well, a couple things. First, try not to be afraid to address any health concerns you have about yourself. By getting something diagnossed early, the outcome typically is SO much better. It is when we wait that we often end up in a complex situation. So, it is better to go to a doctor and tackle something head on with our health.
Second, I had a slow thyroid and had pms symptoms for the full time it took to have a period--- so --- I had periods every 3 to 4 months and I'd start pms after two weeks after my menstrual cycle and continue to have it until my period came due to hormones.
Third, you need to be seen by a doctor to determine why your periods are so infrequent. Sometimes being signficantly under or over weight can cause that or like in my case, an issue of the thyroid (mine was too slow). They can then work to address the problem so that you can have a regular cycle and be healthy. good luck