you may already have had your weekend sex, but I will offer my experise as a lay sex therapist with this - check out my other posts in the "Love and Sex" forum regarding curing premature ejaculation. I offer seven or eight tricks to use to get by this problem. If you can't find them, PM me.
Regarding continuing to thrust after you have cum, your penis will stay mostly hard for a half minute or so after you have cum, so you can continue to thrust if she has not finished, although there is a slight risk of some of the spent cum leaking out the top of the condom. If you have a reservoir tip in the condom this should not be a problem, unless you have ejaculated a large amount of cum.