You are confusing "personal exemption" with the "standard deduction".
For 2017 the standard deduction for each tax filer is $6,050. Additionally each tax filer gets a personal exemption of $4,050 on top of that. So I think if you just re-read the information you have, understanding the difference, that will clear things up better for you, than I can.
Do understand that for a married couple to file MFS, is always more costly tax-wise. When a married couple files separate returns, they both automatically disqualify themselves for deductions and credits they would otherwise qualify for if they filed a joint return.
It does not matter that only one of you had income for the tax year either. It is still better to file a joint return.
We file separately because of student loan implications.
Ah I see. But I would suggest you test it out by working it both ways to see which is better. Generally whatever you save on lower loan payments, you pay for in lost tax deductions. So you can pay six of one, or half dozen of the other - whichever you prefer. But I would think you would want to get that student loan gorilla off your back as soon as possible, by getting it paid off as fast as possible. Filing separate still costs you, and you can't deduct what you pay the IRS instead of the lender, from *anything*.
