Am I overreacting?

I’ve been with my now fiancé for almost 5 years and not once has his family treated me like I’m apart of the family. They went 4 years without realizing one of the 365 days a year might be my birthday. This year his mother handed me a card and said “sorry I forgot all these years” we have a 2 year old and I have a 7 year old from a previous relationship. They treat my oldest son the same as my youngest. They don’t call or text to ask how they are but we see them on holidays. Anyway, they have never done anything for Mother’s Day but since having our son have always praised my fiancé for being a dad (that’s it’s own story) and always have a special lunch for him. I told him that it upsets me that they don’t recognize me on Mother’s Day (not even a text or phone call) but go all out for him on Father’s Day. He told me I’m being unreasonable and childish. This year we had already planned that Father’s Day and my brothers birthday would be celebrated together at my moms. He’s was fully aware since Mother’s Day, but yesterday his mother texted him that they’ll be having a lunch for him at his grandfathers house. I told him to go that I had already planned to be at my moms to see my dad and brother. He has turned it into this whole thing. Am I in the wrong?