Am I considered resident alien for tax purposes in 2019?

Hi,
My first entry to US was in April 2014 with a single-entry F1 visa. I then departed out of US in May 2015 to visit my family and applied for another F1 visa. the whole duration I was out of US was almost 70 days and I got anohter single-entry F1 visa and returned to US in July 2015 and resumed my studies. I still had the same SEVIS. Since then I never left US and my status has been always F1. (in 2016 I got my status changed to F1-OPT and in 2019 changed back to F1 with same SEVIS as my first entry in 2014)  
I know there is a 5 year exemption for substantial presence test. Should I consider my first entry 2015 or 2014 since I got two different F1 visas? in either case will I be considered resident for tax purposes?
I appreciate your answers