Is anyone like me?

I’m just sat here confused about why my personality is like this. I am so quiet to a fault around people that I am not familiar with. I struggle to make friends because I wouldn’t have the courage to initiate conversations. I just prefer my own company. I don’t stand up for myself when I should. This can’t be normal for a 32 years old! My worry is that I don’t want my daughter to take on my personality. I want her to be outspoken, to be able to speak up for herself. How can I model that if I don’t do these things myself? Earlier today, I went to the local supermarket and the shop assistant was so rude to me. Instead of telling her not to speak to me that way, guess what I did? I just walked away and went to another shop assistant to ask for the item that I was looking for. It was AFTER I had left that I was like “did you really just walk away without telling her to not speak to you in that manner?! Go back!”. Well I couldn’t go back because it was too late. This happens a lot… it’s after I have stupidly walked away then I start thinking what I should have said instead. I really don’t know why and how I can get myself to be more confident