No DLC? That's always fun.
In your case, there's aesthetic and technical aspects that could be improved.
By the way, you didn't post a screenshot from landing or right before touchdown. Please fix that next time.
How heavy was that payload? 10% of that 442t entire mass would imply a minimum of approx 45t. With those tanks, it looks like your payload was about 20t? Not heavy enough for that rocket mass.
So either you need to make the payload bigger, or the rocket lighter, or some combination of both.
View attachment 108530
It looks like you still have lots of your main tank left before landing, about 20%?
And is the other tank for the cargo door or something else?
In any case, extra fuel is worse than useless, it hurts your performance. You could drain some tanks in the buildscreen so you start with a lighter shuttle, gaining efficiency. Or you can swap that extra fuel for more payload.
It's nice that you tried to have a proper hinge, but it's not necessary, and if your shuttle has a "pop-off" door instead that can re-attach, it might look nicer and have extra space for more payload.
Your distribution of parachutes and RCS is not very aesthetic or aerodynamic, I would try clipping or hiding them. Overall you should make your shuttle sleeker, and try make it lighter by finding unnecessary things to delete.
There's no pictures of it, but I suspect your boosters run out of fuel close to the same time as the first stage. That's inefficient, better if the boosters run out well before the first stage does.
Also, your shuttle might require a greater TWR if it detatches from the first stage at close to 1000 m/s. Maybe three valiants?
I suspect that with the appropriate modifications, you could make your shuttle, first stage and booster a lot lighter.