Sorry just read my last post and I didn't mean to make assumptions about the BFing!
About the surge - it's a wee surge of lutenising hormone which tells the ovaries to release an egg... They always happen prior to Ov but you can have one and then not ov... generally though you get a positive on an OPK 12-48 hours before ov so you know to BD like crazy if you get a pos
You are probably best to get a themometer though if you have irregular cycles at times and then you can confirm ovulation with a sustained temp increase...
Come join us in the charting thread

have you had a look on fertility friend it gives you heaps of info on charting