10+ years with the same company: my only relevant experience

I’ve been with my company for over 10 years, starting shortly after college. I began as a marketing coordinator at a financial firm and have worked my way up to a regional senior manager role. As I update my resume, I realize that all my relevant experience ties back to this one company, which I know can be a challenge. I’m focusing primarily on my current role since it’s the most relevant, but I’m unsure how to present my previous titles. Should I list each one separately or group them together? And how many bullet points should I include for my earlier roles?

Another major struggle is that while my focus has shifted to higher-level marketing strategy as a senior manager, being short-staffed means I still handle many of the same tasks I did at lower levels—just on top of everything else. For example, I worked on proposals as a marketing specialist, but I still do them now. Should I list that under my current role, or should I include it under the specialist role to strengthen that section?

Any helpful tips would be greatly appreciated! Thanks in advance.