I have always had a very poor memory and as a teen I remembered very little of my childhood. No - it desn't mean that you were abused. What it probably means is that you are like many, many people on this planet who don't have great memories. The majority of people don't remember their childhood clearly. I know many people who can't even remember last year clearly.
It sounds like you are shy. That is normal also.
There are medications that can help if you have difficulties with anxiety or depression.
Shyness has a large genetic component - so does anxiety and depression. It doesn't mean that you were abused if you have these things.