The testicles can change appearance - and I know in stressful situations they can even be pulled in closer to the body (my instinct says for protection)... a very good design implement for a male mammal
:lol:
Heat is also a big factor depending on where you live, and it doesn't take long for it to zap those little swimmers and a while to get them going again (if you could put your location in your profile on the left... doesn't have to be specific, but it helps the community answer/troubleshoot a bit more accurately).
Did he have a good fall off, or just mount and lose interest? Being young and inexperienced it might just take him time to figure out the mechanics of it all. If you have wire cages you can look underneath and get a better idea if the doe is lifting or has her butt planted, if he is hitting the mark or just flailing away, etc.
When you say 30 days after initial breeding, is that now? If so there is still plenty of time for her to have kits. It's not always easy to tell if they are PG. Keep a nest box in for at least another week. If she is a first time mom she might not get it figured out exactly right.
Also, how aggressive was she toward him? He might be a bit afraid to approach now (which would explain the suck in testicles). Or he could be over weight and lazy
What time of day are you trying? They are most active at night and in the AM, by afternoon it's siesta time!
Lots to think about - just trying to think through all the scenarios based on the info provided.