Blood Work Needed?

Hi ladies!  My DH and I have been trying for 14 months, with issues on my end (possibly short luteal phase).  I have been to the RE a few times, and if this cycle doesn't result in a BFP, I'll be on Clomid and try IUI on the next few cycles.  However, I've only had ultrasounds, but haven't had any blood work done by any of my doctors.  
​Should I ask for some blood work tests before I start the next round? I'm not sure what exactly they test for, so not sure if it always needed or not. 
Any suggestions or thoughts are much appreciated!!  Thank you so much, and good luck!