Suspension question

Hi everyone.
I have a 2016 Defender 90 which has been 'fettled' with in order to make it more road-friendly and 'sporty'.
I bought the car from a well-known company who specialise in this.
Part of this process was to swap out the OEM suspension for Bilstein B6 dampers and different springs with a 2" lowering kit. It's also running 18" sawtooth alloys with BF Goodrich tyres.

I've been running it for two years now and covered 10k miles. Unfortunately, I have a degenerative neck issue which means that I'm extra sensitive to any bumps and jolts to that area and I'm finding the ride in the car increasingly harsh.

Can anyone recommend any reasonable solutions and advise me whether this issues can be mainly solved by changing the springs and/or dampers - or whether it's the 18" wheels that are the main cause?

I like the way that the car corners, etc but I'm thinking that I might have to sacrifice some of the car's handling ability in favour of my comfort! I'm also currently running the tyres at 26psi (instead of 35 to 40psi!!) to try and take the edge off things - but that's not really helping much.

Any constructive suggestions would be welcome. Many thanks.

Are you running AT's or SAT's, neither of which, in my very humble super-qualified opinion, give an exceptionally smooth road ride due to the tread patterns which create a 'rumble'.
I run on commercial 7.50 Michelin road tyres, keeping a set of SAT's for off road stuff and, with them being 'van tyres' they are a smooth and comfortable road ride running at 28 front and 32 rear.