Follicle Scan and Trigger

I am on CD 9 and just went in for a follicle scan. On the right, I have a 18mm and 16mm. On the left, I have a 14mm and a 13mm. My nurse said I may need to trigger tonight and have timed intercourse starting today. Will my 18mm be the only one to probably make it? Or could any of the others possibly work?