Im confused about my girlfriend?

me and my gf have been together for a little over 3 months and her mom doesnt like her coming over to my house. we live about 5 min away from each other and wenever she asks her mom her mom just kinda gets pissed and doesnt say yes or no. my gf doesnt like argueing with her mom and she doesnt ask much now. her mom also doesnt like us basically touching. her sister whos older and has a kid used to have this problem with her mom and i think this is why shes like this with my gf but wenever me and my gf try to talk about this we both get frustrated for one and if i say how much wut her mom does annoys me she takes it as me throwing it in her face. thn we get all quiet and both look mad but we tell the other one were not. wen im alone i think about this and how i really want her to come over and hang out cuz my house is the only place where we can hug or kiss and not have to worry about sumone getting pissed. but sumtimes i get like knots in my stomache and upset tht i nvr have her over and lately i havnt gotten to hangout with her much. wenever i try to plan a day to hangout she just says idk mabe and doesnt ask her mom if shes allowed or not and tht upsets me and makes me feel well idk and thts why i just ranted about all this idk wuts wrong (with me or in general) and i was hoping sumone would explain it. if u want more specifics just tell me thank you this really is the only thing i can think of tht might help me figure stuff out.