i know exactly how you feel! i've been in the church forever, and have recently been struggling a lot. through a horrible combination of circumstances, i've had to move back in with my parents-after being on my own for 6 years. i, too, have often felt empty and betrayed by god. i mean, my rationale went, if i'm doing what's right, life should be easy, right?
but what i've recently learned is that god gives times of growing and stretching. once we learn what he wants us to, he tests us. he's not abandoning us, we're abandoning him. it's like we're saying 'well, god, i've done my part, give me blessings!'
you say you want to have children. that's awesome. but when you do, will you just give them whatever they want and go out of your way to make sure things are easy for them and that they don't get hurt? of course not. because being hurt, and picking yourself up is part of the experience. i think what i tend to forget is that god is a perfect version of a mortal father. he knows what's best for us. and sometimes struggling is the wisest course of action. it actually turns out that people value the most what they have to work for. would a promotion mean as much if you were just randomly selected in a lottery, as opposed to working day and night for it?
i guess what my jumbled up message is trying to say is that, while things are bad, keep trying. i've tried punishing god by not going to church, reading my scriptures, or praying. and it only hurts me. even though you may not feel the spirit, or feel like god is there, he is! my mum used to tell me (about being nice to others) fake it until you feel it. sometimes that's what you have to do in the gospel. pray, read, go, even if it feels like you're wasting your time. you won't be.
and as for feeling like you have dissappointed everybody, you haven't. because you're concerned about it shows that you care. and i'm sure god is pleased that you haven't given up all the way. but perhaps you should talk to your bishop and the missionaries, maybe even the people that you are staying with. see if they can offer advice, or at least compassion. tell them how you feel. i realize that's a very unmanly thing to do. but sometimes people give offense without realizing. i think a blessing would help you, too.
well, i hope that helps a little bit. all i can say is that i will pray for you, and hopefully you pray for yourself. good luck!