We have been trying for a while, not complaining but, he has not been able to cum.
Online sites are great for getting information about conditions and issues, but it can not take the place of your husband's doctor. If you think he is having a serious issue you should make an appointment.
There is a condition called Retrograde Ejaculation where the man can maintain an erection but either has very little ejaculate or none at all, called a dry climax. You can read more about Retrograde Ejaculation here.
Hope this helps. Make sure you get him to get a check up and let us know how you are doing!!Best,