What Job Title Should I Use for My CV?

I'm currently on the job hunt but I'm unsure what title to use when marketing myself. I want to ensure my CV reflects my experience accurately. Here's a quick rundown of my career:

- At Company A (an e-commerce giant), I worked for a year in the QA team right after graduating with a BSc in software engineering. I built pipelines, created mock services, and set up testing environments.
- Then, I spent three years at Company B, a large industrial center, where I focused on automating app deployments to Kubernetes. This included writing code for zero-downtime deployments and architecting parts of the Kubernetes infrastructure, including custom load balancing and proxy management. I also provided support for our clusters on a rotating schedule every four weeks.
- For the past three years, I've been freelancing. My main achievement was building a last mile delivery system for a mid-sized company that is now used by two others as well. The system encompasses everything related to package management and includes websites for various stakeholders and an Android app for couriers, which I created using AI tools in just two weeks.

Given this experience, I'm torn between titles like Platform Engineer, Site Reliability Engineer, DevOps Engineer, or something else entirely. Any suggestions? Oh, and just a quick note: if anyone has job offers, I'm looking for around $40/hour!