I don't think you're pregnant either.
My girlfriend had something similar. She had some discoloration with her discharge and her vagina seemed to have a lot of discomfort during sex. Like a burning sensation.
From what I remember, she just had a yeast infection which as bad as most people view it. It's common infection that gets treated all the time.
I recommend you first, calm down. If you didn't have sex then there's no way you could be pregnant unless you or your boyfriend actually put the semen in you. Second, either go get some kind of antibiotics or simply call a pharmacist. Just tell them your symptoms and concerns and they should respond with a reliable answer.
Trust me, I've done it a lot.
And for your irregular period, since your only 16, there's a high chance you're body is still going through that hormonal balance process which results in irregular periods. You (and I'm speaking in general for most girls) should get a regular monthly period around the age of 18. ALSO, from experience and past knowledge, once you begin having sex, your period may go irregular again. What you can do to not freak out like my girlfriend and I did for two months, is USE PROTECTION. Always check afterwards if the condom broke or not. Eat healthy and be open with your partner. From what it seems you two are pretty close. I'm happy for you guys