Could I be pre-menopausal? Please help...?

I have been taking fertility treatments for a while. I had an IUI with fertility shots two months ago. Last month I started my period as usual and had severe cramps as I always do. This month I spotted for a whole week before having a heavier flow, but I NEVER had cramps and I'm not really sure I can pinpoint the first day of my period because it was so weird this month. In all my period (spotting and actual flow) has lasted for two weeks. I had an IUI with shots in March and the next menstrual cycles were normal. What worries me most is that I had no menstrual cramps - I ALWAYS have severe cramps usually lasting two days. Could the fertility treatments send me into early menopause? I'm only 31.