Hello my name is brittany I'm 19 years old and I've been having problems with my menstrual cycle for about 2 months now. My last cycle was January 2nd, 2013. I've recently went to the clinic because I've been having pains in my lower abdomen when using the releasing urination or bowels. The doctor I'd seen took some tests and x-rays. There was nothing seriously wrong and I wasn't pregnant. But I did find out that I was backed up with bowels and constipated. I don't know if that has to do with my cycle not showing up or what but I'm starting to get worried I've never missed more than one cycle in a period of 2 months. And last July, it hasn't even been a whole year yet, but my primary care provider did a pelvic exam on me and a week later told me I had the STI called HPV. On February 27th, 2013 I experienced vaginal bleeding I thought was my cycle but only lasted for no more than 4 hours. This to me was abnormal I usually stay on my cycle for about 4 days and come on about every 29 to 30 days but I am used to my cycle being irregular, however I just know that I stay on for a total of 4 days. Needless to say I'm nervous about this all I try to set appointments for my OBGYN but always get a date for a month from now. I just want answers now. I don't want anything to be seriously wrong that might affect my future of having children

Because of the HPV you are at increased risk for cervical intraepithelial neoplasia which may later become squamous cell carcinoma- however I don't think this explains your current symptoms. (But, continue with normal yearly checkup, to keep this controlled!)

From what it sounds like, you may have endometriosis. Which presents with pain with bowel movements, intestinal obstruction during meses, pain during intercourse, pain during menses, missed or abnormal periods, or inter-menstrual bleeding.
This is caused by abnormal glands and stroma growing outside of the uterus which causes pain and even irregular menses. Don't worry it's not cancerous! But, it can be painful and can increase the risk for ectopic pregnancy or infertility (but many women with this do have children!)

I don't know what tests your doctor did, but you might bring this up at your next appointment.