My Fiancée is Pulling Back and I Don't Know What to Do

I don't know what to do anymore. My fiancée has been pulling back for a couple of months now. She doesn't give me attention anymore. Instead she just watches TV and looks at her phone until she goes to sleep. We used to cuddle, kiss, and look at each other leaving an open window to talk about our days or anything bugging us. Now I have to beg for her attention and it just doesn't feel right. I shouldn't have to constantly ask for attention, right? And she says she wants me to initiate sex too but every time I do she always has an excuse. They're valid but something's always up. Either she has a headache or a stomach ache or she's too tired. I'm tired of trying all the time to just get turned down. And she wants me to initiate by making out instead of asking but how can I make out with her when she's glued to her phone all night? She used to text me first everyday because I sleep in but now she doesn't text me unless I text her first. I've had several conversations with her about her pulling back and she always gets super defensive. What can I do? My feelings are really hurt. We're supposed to be trying for a baby soon too. I'm female if that matters at all.