Wait, your description of the IUD is inconsistent...which one do you have in? If you have the Mirena or another hormonal IUD, you will not ovulate. You also are not likely to have a period. If you do have a Mirena, it needs to be replaced every five years to be effective. Also make sure you're checking the strings to double check it hasn't moved (that's uncommon, but it's good to be safe!)

If you have the copper IUD (Paragard) you WILL ovulate (This is the one I have in). It works by making the vagina a hostile environment where either the sperm will die or the egg will be unable to implant. You WILL have a period, and likely a heavier one than if you didn't use birth control. You will also probably have some intense cramps or as bad or worse than without birth control.

Also, from personal experience, white discharge doesn't necessarily coincide with being pregnant. I have white/off-white discharge off and on and I'm not pregnant. If you have the Paragard in and you used a condom, there's only a tiny, tiny chance you could be pregnant. Now, if it's a Mirena, I can't say since I don't know when it expired. A condom used correctly one time should still be pretty effective.

(Note: Obviously, I'm not a doctor and if you can go to an OBGyn or something that would be ideal. This is all just based on my personal experience and research)