My Fiancé's Stepdad Does Not Want Us To Get Married -- HELP!

I am here looking for advice as I feel like I have nowhere else to go and or to turn to. My fiancé, 30M, and me 26F, just recently got engaged in May and I was over the moon! We've known each other for close to seven years in which five of those we have been dating and living together. His family has been really welcoming and supportive throughout the years and I thought that we were all on good terms. His stepdad owns a small business and does quite well and his mom has just been a stay at home mom since they got together 26 year ago. My fiancé does have a younger brother but he is 24 and living on his own and has been for quite some time. Well we thought that everyone was excited for us until my fiancé's stepdad call him last night telling him that they need to have a man to man talk before we get married. He thinks that we should wait and that we need to maybe not do this until "certain things in our lives change". We have our own house, no kids, 2 pets a cat and dog, he works in the oilfield Monday-Friday, and I work in a lead position at a non-profit. We go on just because trips and we take care of ourselves. His truck is paid off and we have no debt besides my car in which I pay for and I have 2k left on a student loan. I'm so confused on what could change, and when asked about it, his stepdad said well you guys know. His mom one time in the past had a sit down conversation with me where she told me to break up with her son and that I was making him less of a man because of the things that I do for him like cooking, cleaning, yardwork, but these are all things that he helps with so I was confused and wrote it off. His mom and I were supposed to go wedding dress shopping this weekend, but after what his stepdad said, I am not sure if it's a good idea if she comes or not. I feel so defeated...I called my own dad and he told me that maybe I should uninvite her and keep a distance if this is how they feel. I just don't know what to do, I feel like I try so hard for him and his family. Is it me? Do they even want us to get married? I am lost and any advice that I can get, I am open to and thankful for because I am so confused and sad. I feel like they ruined this whole experience before it even got started.