It is very unlikely that you always have your period on the 15 of every month. There isnt always the same amount of days between each month A regular period is on a 21-35 day cycle. and will fluctuate through out your life. So will the symptoms which can be cramping, back pain, bloating, breast tenderness, fullness, nipple soreness, acne, gas, headaches, among other symptoms and severities. It is very common to skip a period and still have symptoms.
None of your symptoms are a huge cause for concern.. But I would see your Doctor as soon as possible for a Blood pregnancy test, and a pap test if it has been more than one year since your last.
Also make sure to tell your Doctor that you have had unprotected sex, and would like a full screening for STI's.
Most people think a pap test will show an STI but It wont.. You have to ask because It is a separate test.
Is it really that weird for your period to be only 2 days late? I'm a bit "passed it" age wise to have to worry about birth control and I realize there is so much new stuff on the market. In my day, most of us didn't have a clue when our periods would show up.
But, I digress.
A UTI should not interfer with your periods. But on that subject, if you've had three of them within a fairly short period of time, you might want to talk to your gyno about them.
If you've never had breast or nipple soreness, or spotting, that would also be something you should discuss with your gyno. The frequent urination is often a symptom of a UTI but it's usually accompanied by burning and a strong odor to your urine. Every 20 minutes is pretty frequent, though. Have you increased your water intake recently? Is the cramping also new for you?
I really don't know what this could be and I wouldn't be overly concerned, but I would definitely make an appt. to discuss all these changes just to be on the safe side.
I'm not a big proponent of the "wait and see" philosophy. I work in a hospital and I've heard "if only I'd come in sooner" way too often.
Peace
Greenlydia