I started on Estropstep Fe about 7 years ago and during that time...

I started on Estropstep Fe about 7 years ago and during that time I switched once to Ortho-Novum (which I did not like at all). Ortho-Novum made me gain weight and just did not feel good on it... So I switched back to Estrostep Fe about 2 years ago and I am still taking them. I guess my concern is that I have been super irregular since i have started back on them. For instance, I will have my period one month and then not have it again for the next two months, then I will have it and then not again for one month and the pattern goes on... Is this normal or is there some underlying thing to this?