Hello! I Am A 25 Year Old Sexually Active Female.

Hello! I am a 25 year old sexually active female. Ever since I was 15, I have had a heavy vaginal discharge, and must wear thin unscented Always brand panty liners (I change them 1 - 2 times a day depending on how active I am), otherwise my panties (mine are all cotton) will be drenched within an hou rin discharge. I frequent UTI's, and when I was 18 I had two Cystoscopies done (i would get UTI's nearly every other time after having sex), which yielded nothing abnormal other than a narrow urethra(Tube leading up to my uterus from my vagina?)As a baby, I couldn't bathe in bubble bath without getting a UTI, and had to bathe in water with sensitive-skin soap. I average 1 UTI / month - 1.5 months, despite keeping hydrated, urinating and eating a cranberry capsule after intercourse, and good personal hygiene (mild - non scented soap SID when I shower in the evening). I have a doctor who prescribes me Macrobid with refills. I have had two yeast infections in my life. About 6 months ago, I started noticing some urine/vaginal discharge changes despite no food / lifestyle change. My discharge was becoming smellier and thicker. It has always had a mild odour to it, but it is very vinegary smelling now and continues to get more pungent. There is much more discharge when I urinate, and sometimes it leaves the toilet water very cloudy, occasionally yeasty looking. I will occasionally feel a slight uncomfortability in my bladder now (once every few weeks), the exact same feeling I get before the pain hits before I get a bladder infection, only it never turns into a UTI, and goes away after 2 - 5 days It almost feels like I have a tampon in that is too big and is rubbing unconfortably on my medial bladder (or uterus?) wall. I went to the doctor who prescribes my medicine, and we have done a Chlamydia & Gonorrhea test, a Pap, a Trichomonas test, and a UTI test, all of which have come back negative. I got an Mirena 5 year IUD put in on Nov 2nd, and have been spotting almost every day since, save maybe 3 - 4 days (it's 11/28/15 today) in the first two weeks after insertion. But now my discharge smell is so strong that I have been wearing light days tampons to soak up the spotting/discharge when I am at work or out of the house, otherwise I can smell my vagina, and I'm sure others can too. When I am at home I have been airing it out wearing loose fitting baggy pants and no underwear / tampon. Do you have any suggestions for what I can do next, or suggestions to get my urinary tract back to normal? What tests I can recommend my doctor test for? He seems to be at a loss for what to try next to determine the cause of the odour / occasional uncomfortability / thick discharge / cloudy toilet water. Thank you so much for your time.