I went off birth control in November of last year and haven't ovulated since. I started Metformin a little over a month ago and yesterday (August 23) I finally got a positive OPK!! My husband was on a night shift last night and he wasn't home by the time I left for work, so we can't have sex until I get home tonight. The last time we had sex was August 21. Did we miss our window for getting pregnant or could I still conceive if we have sex tonight?