Dunno if you're private or NHS, but if NHS, it would probably help to get 3 monthly appointments with a hygienist (Denplan cover this - am sure others do, too). As I've noticed dentists do a quick scale and polish, but a proper hygiene appointment, you get much better attention as well as great advice, and they can help monitor things really well.
My private dentist recently started letting people register just with the hygienist (you used to have to be one of their patients) and I'd guess this is getting commoner, now. My husband is NHS but loves going to the hygienist! Just a one-off payment, he can go, now.
My teeth are too close together so I can't use an interdental brush at all - I use dental tape (prefer it to floss). Think once the pockets get above 2mm, nothing much can really get into them to clean them properly - or at least, a toothbrush can't. My hygienist says to use a soft toothbrush, as well, as that does get under the gumline a bit better.
I've had scales and polishes with dentists but they have never taken more than a few minutes. A decent hygiene appointment might be 20 mins - half an hour (or more) and that makes a world of difference, to my teeth. I'm middle aged too and went for years without a single hygiene visit but have had a lot less issues since I started going.