I'm also worried that even if we manage to conceive #3 we may not actually be able to conceive #4 at all... being that it's taking so long this time.
We're going to try something called SMEP this cycle. Sperm Meets Egg Plan. You basically start DTD every other day from CD8, then once you get a positive OPK you BD 3 days in a row, then miss one day and BD the next day. By then you're in the TWW.
Only issue with that is I don't have any OPKs. I've read and a positive OPK indicates ovulation will occur within 24-72 hours. The only way I have to tell is EWCM, and it appears that ovulation occurs for most women on the last day of EWCM - http://www.smartstork.com/page9.asp. I'll try to watch it very carefully.
CD10 - updated post with SMEP information.
CD13 - we both fell sick with a nasty cold! Didn't manage the 3 days in a row thing. No EWCM this month.
CD21 - felt incredibly dizzy most of the day. Nothing I could attribute it to. Eventually went away in the late afternoon.
CD23 - creamy CM.
CD26 - thought AF had arrived - had brown tinged CM, but it didn't reappear. Mild cramping yesterday and today.
CD28 - BFP! Yeah! Still got it ;) Baby 3 is officially on his/her way.