Has anyone else experienced this?

Holly • TTC baby #2
Hiya :-) 
​Hoping some of you can help me here. 
​So, my period is now 4 days late. Don't want to waste my last hpt unnecessarily and I've read somewhere that if you get a +opk then you could be pregnant?! But also that your body produces LH before AF comes. Is this true? Anyway, have loads of opk's so decided to use one. Well, 3 actually lol. They were all a blaring positive! Has anyone ever done this and got a + hpt? I'm so confused now I might just take the test anyway. Would love to hear from you! Thanks :-)