Yes to laughter and cock rings! And it is lovely to hear how you partnership is responding to these changes.
On your original question, about going from penis getting big to actually getting hard:
For me the first signs of hardness were a bit less than 12 months, and then the next two years it has been on-and-off. Sometimes naturally quite hard, other times unreliable. As I get close to my third anniversary the frequency of real natural hardness is definitely getting more.
As you have probably already noticed, penetrative sex is about the biggest test of an erection. Stimulation with hand or mouth works fine even when not very hard, but penetration can literally knock the stuffing out of a marginal erection.
Also, in the first year, the drugs like Cialis and Viagra made absolutely no noticeable difference, but now I find that 25mg of Viagra makes my erections like they were when I was young. I still don't use it often because it makes my head feel funny, like I have a hangover without drinking.
What works really well now that my natural erections are better than 50% is a cock ring of the sort others have recommended. It is no fuss, no pain, and definitely supports better erections and they last much longer.