When an interviewer sees slow career progression on your resume, they will immediately want to determine whether this is by your own choice, any outside circumstances, or if you just are not motivated to create growth in your career. If your job has progressed slower than you wish, you must be honest with the interviewer when discussing this.
"I agree with you that my career progression has been slower than some. You will see that between 2005 - 2009 I worked for the same company without an increase in my job title. The company was too small to offer a promotion to me as the next level was directorship which I didn't have the educational credentials for. After this, from 2009-2012 I was on leave as I needed to care for my ailing parents. The growth since returning to work has been steady but those years were a bit of a standstill for me. I am ready to spring into action now, and forge ahead in my career as a lab assistant."
Entry Level answer example
"I am happy with my progress as a lab assistant. My education did take me a bit longer to complete than I expected; however, I was working full time in tandem with my studies."
Experienced answer example
"I have progressed comfortably in my career. Although it may not seem as advanced as some, I am content with my progression as it has offered me a manageable pace and the chance to take additional coursework related to my role as a laboratory assistant."