Yes, you can file Married Filing Separately.
Since you have passed the five years not counting days period as a nonresident (2010-2014), starting from January 1, 2015, as long as you stay within the US for more than 183 days or meet the Substantial Presence Test SPT, you are considered as a US resident for tax purposes. Therefore, in 2018, as an H-1B visa, the same rule applies to you. If you pass SPT, you will be a resident in 2018. However, if you did not stay in the US for more than 183 days, your US spouse can file a statement to treat you as a resident. See Nonresident to resident.
As a resident, you can file Married Filing Separately on the Form 1040. You do not have to file the Form 1040NR.
