Next time you do a qually lap close to your best save and share it to your showcase then people can "race" you and tell you specifically where you're relatively fast/slow and offer more pin pointed advice.
Another thing I'll say which is on a tangent but hopefully encouraging for you in some way...
My gallery on GT7 is stuffed full of replays from past daily races over the years. I'm not going to ask you to watch them, but I will say the vast majority don't have me fighting for podiums or wins. Mostly, I've shared races where the driving has been impressively clean, or there's been isolated moments of astute defending or clever tactical moments... From ALL DIFFERENT positions of the grid.
Usually when I watch them back, I end up forgetting that I'm watching P11 fighting with P12, for example.
You know why? Because it's the racing that matters.
A+ isn't the final boss of Gran Turismo, it's just a player filter.