Like you, I have built a fairly complex App using VueJs and NodeJs. Like you, it was my first App in VueJS and I recognise that it could have been better. Having said that it has now gone through five lots of UAT without anymore than a few glitches (The full App has been re-tested every time a new data area has been added), so it cannot have been that bad, I have after all been programming for 30 years, but there are always new approaches in a new language and it takes a while to adjust.
I am not offering to help you as there are lots of better qualified people to do that but I would suggest that you consider the following lessons that I learnt.
a) Consider rebuilding it in Vue3. Vue3 probably needs a little more time for the supporting packages to mature but there is a lot there already, and if you are going to re-write it, then do you really want to re-write it in a version of Vue that is being replaced? If your existing App is running OK, then you probably can afford the time for this.
b) It you haven’t already, use Vuetify as this handles re-sizing well.
c) If you haven’t already, use TypeScript. This offers compile time debugging. I have been using this in my second project, There are some cases when it is a pain, but you can always resort to JS in places. There are perhaps some people out there who are more bothered about perfect types than delivering solutions. Just bear in mind that it won’t stop run time errors so you still need to have checks and handling in your code.
d) Spend time searching for and trying different pre-build components. Awesome Vue has a good list of these if you haven’t found that already. I have been using DevExtreme in my second project, and it is good, not too expensive and the support is excellent. Finding a good off the shelf component can save a lot of time, and it will generally handle resizing, and perform well.