Seeing as the likes of Gallagher and Henderson aren't good enough against the better sides, and Mainoo still lacks experience, I wonder if it might be worth going back to the 5 at the back Southgate used to love. Playing that way eliminates the midfield issue, though Bellingham would have to be more disciplined than the role he plays at Real Madrid. But it gives you extra strength in defence and also would allow you to bring Trent into the side, who regardless of what you think of him as a defender, is second to only De Bruyne in the Premier League in regards to what he can do on the ball.
Walker, Stones and Maguire at centre-back with Trent and Shaw playing as attacking wing-backs. Rice and Bellingham in midfield. Then any two from Foden, Saka, Maddison, Rashford, Grealish, Gordon and Palmer depending on form, fitness and what you want against certain opposition. Kane obviously up top. The biggest issues with that are you would have to play Bellingham deeper, and 5 at the back can become extremely negative if your wing-backs get pushed back. The positives are you can get TAA in the side who brings creativity, and you also have Walker's pace in the centre of defence which is a massive plus.
I honestly can't think of anything worse than shoe-horning Bellingham, by far our biggest shining light in recent games, in to a 2 man midfield in order to get the best out of Trent who has turned up for England once against Malta, and who has very little experience of being a wing-back in a 5.
That doesn't fix midfield issues, it creates new ones. And it still has Maguire in the lineup. If you want pace in the backline then put Branthwaite next to Stones (he's quick and actually good). You can afford one young/inexperienced CB in the back five because the other four are all very experienced players. Plenty of reports saying City want Branthwaite anyway, may as well get him used to Stones/Walker early.