OPK question

[MommaOf2girls]

So I am now three weeks past my mc at 6w4d. The bleeding stopped about 4 days ago and my levels one week ago were 23. I was still able to get a very faint positive on a first response hpt on Saturday. I want to start ttc again right away but keep telling myself that for this first month we will just ntnp. But its getting harder and harder and I'm so tempted to go buy some OPK's since I have no idea when I may O. My question is though, are OPKs reliable right after a mc? I thought I read somewhere that they can give false results with your hormones being out of whack. Just don't want to waste time and money on them if they aren't going to do much help this first cycle before AF. Thanks!