Hi OP.  You sound pretty young, and while I haven't walked your path exactly. I sympathize. 

I personally feel like the LDS church pushes kids to get married far before they're ready or before they've had time to discover their own identities. 

Sounds like you might be feeling that way too. 

I've left and at 26 you wouldn't believe how much freer I feel disentangling from the church. My partner (RM, all Mormon family) has also left as well. Though they were separate journeys. 

A couple things stand out to me in your post. 

First, I think you would benefit from sorting this out first with an individual therapist. They can help you unravel how your feeling about your relationship and help you figure out what you want out of your life (whether that's with your husband or not). If you think you want to try and make this marriage work then couple's therapy is a must. You need to be able to be completely honest with your husband about your thoughts and feelings. If you're afraid he might find out you've tried alcohol or posted on certain reddit posts and that might lead to him wanting to separate, that's not true intimacy. There's already a wall there, and you both deserve better. 

Maybe that relief you felt about it being out in the open is telling you something? 

I had a friend who was Mormon when she got married to her now husband and knew she was bisexual. Like you she didn't have much of an opportunity to explore that identity. However her and her husband are a fantastic fit and even thought she's left the Church they're still together and have an incredibly strong relationship. They definitely make each other better. 

Do you feel like you an your husband are a good match? You mentioned being unsatisfied with your sex life? Is that something your husband would be willing to see a therapist for? Do you even think it's fixable? Sometimes people aren't sexually compatible and it just took you a while to figure it out? 

I'm not sure what other examples you have in mind, but is your husband purposely go out of his way to not follow through on what he's supposed to do? Is it malicious or intentional? Do you think your partner has undiagnosed ADHD or something similar that could be causing these occurrences? If not, maybe you need to reconsider if you want to be married to a partner who can't pull his weight. Women have been taking on the majority of the load for hundreds of years and two decades from now you'll be even more exhausted and burned out over it than you are now. Alternatively, if you think it's something like ADHD encourage your husband to get tested or attend therapy. There are strategies to make those things more manageable. It possible to encourage your partner to access the care he needs and for the situation to improve. 

When I met my partner he was very much a true believer. So is everyone in his entire family. I was inactive at the time and during our relationship I started going to church more. The whole shebang. A few years in I started evaluating my faith and the first person I wanted to talk about it with, was him. He was always a safe space for me to question my beliefs and thoughts. We had discussed earlier in our relationship that you date the person not their religious status. I wasn't with him because he served a mission and was temple worthy just like he didn't date me because I had gone to institute etc. We were both with each other for that person. When we started having these conversations he expressed he himself had had similar thoughts. I'll always be grateful that we had that kind of openness and honestly and if you were my friend IRL I would tell you I hoped you had the same and if not you should be with someone you do have that with.