Follicles haven't grown enough

This was my first letrozole cycle. I went in on cd12 and I had two follicles measuring about 14.5-15mm. I went in today cd 14 and they are still only about 15-16mm. They ended up telling me that I will ovulate on my own probably this weekend so not to take my trigger shot and make sure to have intercourse. They seemed like I shouldn't "waste" my shot on this cycle... but then on the other hand kept saying oh you still have a chance! I don't know what to think.