The home tests are not always accurate. When I was pregnant with my son, I had a negative home test, and then later on I had a positive one, confirming what I already knew.
The milk seems like a dead ringer to me, but perhaps your hormones are screwed up from the IUD, and now off-and-on use with the Pill. You are going to the doctor on Monday, and that's really the only way you are going to know for sure. Try to keep your mind off of things this weekend (easier said than done, I know!!), and don't waste your money trying 12 different home tests. ;-) Good luck.
If you choose to be sexually active, and don't want more kids, you and your partner have to work on finding a birth control method that suits you better. Use your doctor's appointment as a time to discuss this, too. When I was on the Pill, I took it at lunch everday. (It not only has to be taken everyday, but at the same time everyday.) Others set cell phone alarms, or leave the pill pack out where they will see it everyday. It's worth investigating other methods, too. The Nuvaring and the Patch only have to be changed once a week. The Depro Provera shot is once every 3 months. Perhaps a method you use only at the time of intercourse (condom or diaphram) would be a good choice. There are a lot of options out there--good luck!
Lastly, if you don't like how you are being treated at your clinic, find another to go to. Any health professional worth seeing should be HAPPY to answer your questions.