Struggling to conceive

Alannah
Me and my husband have been trying to conceive for about a year and a half now. We're both healthy adults aged 27. 
I've been to my doctor and awaiting blood test results. My husband has also been and given a sperm sample. He has just heard today that he has to give another one, but this is just routine, I can't help but worry. 
Has anyone else ever been through this and can give me an idea if this is normal?
Thanks