For some weird reason the website thinks I didn't pay any taxes through deductions last year - but I can clearly see on my paychecks where that isn't the case. Help?

Did you enter a W-2 with amounts in boxes 2 and 17 showing federal and state tax withheld?   Why do you think the "website" thinks you did not pay tax?  What are you looking at?

I'll go back over my W-2, but it showed me at the end of the process why I supposedly owe - and it says that I didn't have any withholdings.