OPK and BD question

So yesterday I was traveling in the car all day, and I was only able to take an OPK at around 10:30pm when I got home. The OPK was positive, so hubby and I BD immediately. This morning I had a slight temperature dip, and took another OPK around 10am - that time the line was significantly lighter, so negative. I just took another OPK around 20 minutes ago, and there was no visible line. 
Does this mean I most likely ovulated today? Do OPKs turn negative once the egg has been released?
Thanks in advance for all your help. I had a miscarriage in April, and this is my first time using OPKs and chatting.