You don't need a second opinion. If you wanted that, you should have gotten it when he was lame and his feet were hot. You cannot confirm the diagnosis of an old case of Laminitis unless you also have Founder. It does not sound like you have Founder, but only had an episode of Laminitis that he has recovered from as he should have.
What you need now is a second set of x-rays that your present Vet can compare to the first ones taken to confirm that you have no rotation.
If you only had Laminitis to begin with, he should have been sound enough for light riding within about 2-3 weeks from the time his feet were cool and he was not lame. This should have been confirmed by a second set of x-rays before then.
The only time it takes 9 months to a year to get a Laminitic horse to that point is if there has been rotation and Founder. Then, once the Coffin Bone has been stabilized, it takes that long to grow down a new hoof. Then, you still need periodic x-rays to confirm that the hoof is healing inside and the amount of rotation is lessening and not getting worse. This is why some horses are permanently unsound when they have Foundered.
There is much confusion about the difference between Laminitis and Founder. Laminitis is strictly the name for inflammation of the sensitive laminae in the hoof of a horse. Every Foundered horse has had Laminities. Thankfully, only some of the horses that have had a bout of Laminities will go on to Founder.
Laminitis is frequently a 'wake-up call'. It can have many causes, but one of the causes seen most frequently is obesity in horses, especially horses with thick, cresty necks. It is the horse equivalent of Type II Diabetes when it is. Other causes are sudden grain or rich grass over-load -- like when a horse gets in the grain room or is turned out on really lush spring grass. Some horses get Laminitis at the drop of a hat and others cannot be given it, even with terrible management. Any horse that has had Laminitis is usually more prone to getting subsequent attacks later and should be managed more closely.