Meeting his family

I’ve been with my boyfriend for a year and three months now which I think is more than enough time to consider meeting each other’s family. He always comes round to my house and has met my parents several times and even my extended family on special occasions (birthdays). But he’s been very reluctant to invite me over when his family is there I only ever go round if they are out. I’ve spoken to him several times saying that I would like to meet them and he always says ‘around Christmas I’ll invite you’ ‘for my birthday you can come and meet them’. But all these occasions have passed, they know about me but I feel like they have a bad impression of me if they have properly met me yet. I met his dad once while I was over but not properly where I was about to introduce myself.

I don’t know what to do or say to him maybe he just doesn’t want them to know about me?