I would say you are ok. I have a lot of days when my OPKs have no second line and I O just fine. I usually have a gradual increase. It will get darker every day (with maybe one with no line in the middle some where) then a positive then it will go back down gradually. I dont really have a certin time during the month that I have no line it could be right before or after O but I have it. Also you can have EWCM and not O right after. I would DTD anyway just in case just keep checking your OPKs to make sure you dont miss the window. I think you are good to go. To be safe try using your OPKs from day 8 until you get a negitive after your positive and temp to make sure you get that thermal shift so you will know you Od. Good luck this week and you can try cheappregancytests.com for cheap OPKs. They work better than Answer brand for me. Good luck with that
