Can i still upgrade to ios 8.3 now that 8.4 has been released?

No, why would you want to?

Apple does not support upgrading to any version of the iOS other than the most recent version supported by your device. Apple also does not support downgrading the iOS. I suggest you start a new question that gives a good title to a specific problem. Then in the body of the thread describe the problem in detail, tell us what steps you have tried so far to correct the problem, what happened, and what error messages you received.