Hello, I’m new to DnD, I know it’s probably sub-optimal, but I want to make a fighter wizard multi-class build

I’m planing for my character to be a teen or young adult, who was studying to become a wizard, but then (depending which campaign we end up doing) either a war happened, and they got forced/drafted into that, or some monster or big-bad attacked their village, killing almost everyone and destroying the village

And because of this, they had to adapt quickly to survive, and became a fighter

I personally like the war backstory more, but I’ll do whatever fits with the campaign

The exact build I do will depend on how optimized my other party members are

If they are super optimized, I’ll go variant human, with cross-bow expert, 1st level fighter, 2nd level wizard, 3rd-6th level fighter, get sharpshooter, and go battle master sub-class, then the rest into wizard, idk what sub-class

If they are not super optimized, I’ll go 1st level fighter, 2nd wizard, 3rd and 4th fighter, either echo-knight or battle master, the rest wizard

Idk if I’d want go shield and rapier, shield and quarter staff with polarm master, or a two handed weapon

Any advice on my build or backstory or character? Thank you for reading this!