Phew, it can be tough to figure out both challenges: backend and frontend.
So, get someone else to figure out the frontend. Create an imaginary friend (user) & give them a motivation or goal.
Starting with a defined goal usually means your problem space is smaller and more defined. Your situation goes from "would this element have enough space" to "Can they see what they need?".
Once you have a user's goal, think about how your interface supports that goal or solves the problem.
Here are some quick examples of user goals / jobs, and how to manage the interface challenges:
| Customer / User | Primary Need or Problem | Frontend helps by... |
|---|---|---|
| Sam the shopper | Buy a product | ...dividing the screen size into regions, so important elements (price. name and image) show above the fold |
| Norm the Newb | Learn something in a blog post | Keeping the top blog navigation minimal and small, so users can focus the main body text |
| Jane the administrator | Update email address | Showing breadcrumbs at the top, to allow for wayfinding. Sizing the SAVE button so it can be tapped with a finger. |
...and just getting a simple page looking decent in 3 different form factors felt like it took quite a bit of work, so for any user interface with more complexity, it starts to feel daunting pretty fast.
It sounds like you might be creating React components from scratch, instead of using a library. Hard work!
At work, we use a phrase to describe the end-to-end experience for the highest priority scenario that we want to happen: "the golden transaction".
I remember the first time I started designing a page layout from scratch with CSS. It was so daunting to try to create a system that could be reused across many different experiences, while also trying to make each page "look cool". I wanted to give us and just go back to HTML 2.0 and use a grey background and Times New Roman font with paragraph tags!
Consider only creating React components / frontend experiences you need for your golden transaction, then branch from there. Good luck!