Songs aren't showing up on iTunes?

I have 76 songs on my iPad and when I go onto iTunes (via laptop) only around 20 of them show up? (Along with CDs I have put on there but not synced to iPad)

I think it is because I have connected my iPad with a different laptop before but I haven't synced/downloaded music from that one?

What can I do to get all of them there because I don't want to sync and lose my songs?