I've been in a similar place as you, but I'm nearing 40 now. We've made it work.

• stop watching porn so much. 1-3x per week is a lot, and it sounds like you dont think you can stop or youll "slip up". 1x every month or two is more "normal". Don't tell her when you do, it's obviously unattractive to her
• your wife probably won't "desire" you. Tell her you're unsatisfied, and you want it more often. Don't even being porn into it
• once you stop spanking you monkey so much, you'll realize your body wants sex. Take that energy on your wife, don't go for porn.
• read /r/marriedredpill. There's a lot of stupid advice there, but the overall theme is something you need