Hii , Welcome To HCM & Thanks For Asking Your Query Here From the medical history you provided most probably your problem is not related to sexual activity as sex life actually has positive effects on ur body as u r 34 yr old , it is very much likely that your hormones are out of balance & its pretty much depends upon your over all physical and psychological health variety of reasons are there which can alter your monthly cycles at this age including - hormone imbalance , thyroid issues ,PCOS etc , Most of these are very well treatable but it needs thorough medical check up and investigations before making any confirm diagnosis & treatment i would strongly suggest you to see a Gynecologist to rule out any underlying medical condition and get it treated I hope it help Thanks & Get well Soon