Hi M.-
Having a cold/virus is not a problem, although it could be hardest on you having to be patient while be feels miserable.
With regard to knowing when you ovulate, I would highly recommend the Creigton Method!http://www.creightonmodel.com/
We have used NFP methods since the beginning of our marriage (12 years) and have been using this method for the past 7 years. All five of our children were "planned" (no "mistakes" or surprises)and because we knew when I started to go into the fertile phase, when it was peak, and when it was the end of the fertile phase, we conceived each time without any problems. You observe your mucus at every bathroom trip and chart it at bedtime. The method is very easy to learn and cost virtually nothing! It is so great to be in touch with and know your body so well.
Another great thing about this method (or any NFP method) is that my husband an I share our fertility. We are both closely involved (I observe and he asks "How are your observations? and charts).
With the charting/method, you know which days are the best days to use for having intercourse. The Creighton Method has certified teachers all over; you probably can find one in your area. They can get you started with charting right away and can be contacted whenever you have questions.
Although I don't have any experience with this or even know if it pertains to you, I have heard that women who come off the pill to get pregnant can have a hard time conceiving right away.
One final note..I am a woman of faith in Christ Jesus, and each time we were ready for another child, we always brought it before the Lord, in prayer. We would pray together as a couple right before anything else "transpired". His will was always done.
I hope this helps. Good luck and may our Lord bless you with the gift of another child!
C.