Scared of Infertility or Babies?

Ok so my husband had yolksack seminoma testicular cancer three years ago. He went in for surgery the day after our first date, got it all taken out and a couple months later the week before his 30th he was told that the cancer came back and was in his lungs (hes a smoker) so he went in for chemo, he made deposits at the sperm bank and they have been there since the chemo.

We got married Sept 2010 and we just bought a house....now its time for babies, but anytime it gets brought up he either shy's away, changes the subject or plain out ignores...his mother wants grandbabies like now and I am nearing 31 so I am in my prime. He said we can start trying after his birthday which is in March but something tells me that he is not wanting to because he is scared. (He has a tendancy to post pone things and just not do whatever it is because he is scared of the outcome or the what if's) He would be a wonderful father I see it when he interacts with the nieces and nephews...but would his fear be coming from.

The chance of being infertile?,anytime I ask him to go get tested he puts it off till the next time... Growing up? Mixture of both?

I know this is a mens forum but any advice would be awesome at this point.