Good luck with the interview.
For the future - don't undersell yourself. You're trying to convince people to hire you. No one is ever a 100% fit for a job. So always think about what it is about you that's an asset to the position you're applying for. If you don't have experience - maybe you have enthusiams and ability to learn. If you don't have people skills, maybe your organisational ability will be enough and you can commit to improve your management skills.
And never underbid for a job. Ideally, as much as you can - ask them what they're offering. If they ask you, see if you can get away with saying, a fair market wage commensurate with my skills and qualifications.
If you do have to give a number - research the field and put in the number that is average for someone who holds that post (so look at the job pay - not how much you should be paid cause you have 5 years more or less than the average person)