Is there a way my boss's could have messed up my taxes ? Some look strange from year to year

For federal withholding?  Each year is separate and changes.  There have been major tax changes the last 3 years.

For one thing the IRS changed the withholding tables so you got more in your checks during the year instead of a big refund.  Or there are other tax changes.  And any  dependents you have are a year older.  If you made more income that can reduce some credits you got like the EIC.  

If things look strange you should take it to your Company HR department for clarification.