vaginal itching?

I read your other post but I have some questions. I know you're embarassed but it would help to know what item you used. You could be having an allergic reaction to it. If it's a rough material you could have scratches or small cuts from it. If you've rubbed or scratched in that area to relieve the itch that would explain the burning sensation. That is very tender flesh and it is easily irritated.
If using the object is totally unrelated you could have a yeast infection or bacterial vaginosis but both of those cause a discharge and you said there is none.
Is it at all possible that you have an STD? You said you were waiting until marriage but you also said you're on birth control, which makes no sense. If you're too shy to go to the doctor you can always buy a kit to test for a yeast infection and treat it with over the counter medication. You can also buy STD testing kits that you mail off.
Good luck.