Tax Dummie Here, OWING SO MUCH HOW?!

Hi everyone, I want to admit that I know very little about taxes and need to be better with budgeting in general. But I was wondering how someone could go from getting refunds almost every year of taxes to now owing thousands (3,000) federally and not have changed any part of my w-4 since working here. I have made maybe 5 dollars more over the past 6 years of working here (working hourly as RN) but this is now the second time I have owed. Last year I figured it was because I went tax-exempt on my couple of bonus pay stubs but this year didn't do that and now I'm owing more? I have requested to look at and change my w-4 but I'm just not quite sure how this happened, as I pay taxes on every pay stub yet it's still not enough?! I know it's minimal info, but any thoughts or advice on how to prevent this from happening again would be appreciated! Thanks!