Difficulty showing feelings outwardly

I don't normally post on this part of the forum so please forgive me if this has been asked before.

I grew up in an atmosphere of significant emotional neglect. It wasn't intentional but a by-product of my mother's mental illness and other extremely difficult circumstances when I was young. There was considerable fear in the house I grew up in as a young child. I also had a difficult time at school due to bullying and having no friends.

I've come a long way in dealing with my past, mostly through therapy but also journaling. One thing I find really hard to deal with is my difficulty in expressing feelings. No matter how I feel inside, nothing shows on the outside. I'm nearly always expressionless. The exceptions are when I have managed to cry a little bit in company (usually in therapy) but these instances are pretty rare. It's not just negative emotions but I find it hard to show happiness or show that I'm pleased for someone's good news, or my own. I feel those things to a greater or lesser extent, but the feelings don't translate across.

It seems logical to me that the atmosphere I grew up in made it important for me to hide how I'm feeling no matter what. I'm also naturally an introvert, so I'm not someone who carries a lot of energy in interactions.

Does anyone else experience this? Have you found a way to deal with it? I probably should say that I'm also really paranoid about my looks to the extent that I believe people are always thinking about how ugly I am when I talk to them. This puts me off showing too much in case they think I look even worse. So I guess there are a lot of factors that contribute to it.

I feel I can't connect properly to others because I look as though I couldn't care less.