Thesis submission isn’t a final domino being knocked over. The process of doing a PhD is rarely so tidy or organised. You get to submission through success; it could be a messy sequence of events over several years, yet in the end you achieve enough. A series of successes leads you to where you need to be.
The PhD process can sometimes be really messy, so take care in your viva preparation to reflect on your successes more than the mess. Remember the results that got you where you are, rather than the barriers that got in your way. You will have learned through mistakes and failures too, but it’s reflecting on the success you’ve found that will help you get ready.
Remind yourself of how you got to the achievements you have now.