I have too at times struggled with whether or not the Church is true. You can get all the spiritual feelings you want, but God doesn't just force or let us rely on these alone, though that is part of it.
There are certain doctrines that if you put into practice, you can see for yourself whether they are or God or not. There are things like tithing, or the Word of Wisdom that you can practice you see if what the Lord promises if you obey them actually happen.
For example, the Word of Wisdom says that if you live it, you will run and not be weary, or you will gain great treasures of knowledge, etc. So live it and see if it works.
Or with tithing, live it and see if the windows of heaven are opened to you or not.
If we covenant to do things for God, and do them and God fulfills his part, then you will know it is of God. If you follow the principle and things go sour and things go awry, then possibly it isn't of God.
We have been in financial straights with the job and a flood in the area lately. Our home got flooded, and I lost my job right off the bat. I have had a couple fly by night jobs since then, however, we have continued to pay tithing. For some reason, we have been able to make the mortgage and meet our needs these last 6 months despite the difficulties. Our bills have been met, we haven't had to ask for Church assistance or welfare, and we are still coasting along despite having alot less money.
So find some principle and test it.