First, know that I consider myself to be a far worse sinner than you have ever been. The following applies to you only if you have some reservations regarding the real presence of Christ in the Eucharist. If not, please skip this paragraph. If you leave, you will essentially be walking away from Christ for the sake of a personal comfort level. He lives in the Tabernacle and you receive Him - not bread and wine - at mass. It is a sad fact that no other Church, outside of the Orthodox, has the true presence of Christ.
Do you spend holy hours? If not, why not? Not even 15 minutes on a regular basis? We are called to love Jesus Christ as He loves us. If so, we then desire to spend time with the One we love. No better place for spiritual solace than in the presence of your Lord. If you have difficulty accepting the presence of Christ in the Eucharist, this is an even greater reason to go before Him in prayer. Tell Him of your troubles and doubts. Ask Him to reveal to you that He is there. Then, if you are as patient with Him as He has been with you, you will receive your answer. As Fr. Benedict Groeschel says, “Once you are aware that He is there, you will be changed.”
As well, you might want to explore some different ministries and/or associations in your parish. Even so, the families with whom you associate have been placed in your presence for a reason. And, you have been placed among them for a reason. Believe it or not, you can learn from them as they learn from you. I am guessing that they are pro-life while you are more social justice oriented. Great! Both are legitimate concerns of the Church. If those others tend to make you feel inferior due to having smaller family, make sure that your concern is warranted, then gently let them know that. As we have just seen in our celebrations of the Advent and Christmas seasons, raising even a single child is of eternal and infinite importance to God.
And, sadly, to be a faithful Catholic these days can tend to make one appear conservative by contrast with the surrounding culture. To be Christian in any sense of the word means that you accept the cross of counter-culturalism that comes with it. You accept the criticism, the suffering, the exiles, if you will. Your life in Christ includes a walk along the the Via Dolorosa. Each of us has veered a bit off the path during our faith journey and we all need occasional course correction. If you have had angry of resentful thoughts regarding your parish, confess them! Nothing better than to leave that confessional with some spiritual guidance, and knowing that your sins are gone.
One other bit: if you feel alienated from others, insulted, belittled or shunned by them, this is a clear call for you to offer prayer for them - which leads directly back to the reason that you became Catholic in the first place: our Lord Jesus Christ - Emmanuel - present among us. If you can manage even 5-10 minutes per week in His presence - on the way to the store or coming back - I guarantee that you will leave the chapel more refreshed than you arrived.
For me to leave the Catholic Church, I would have to renounce Christ. It is just that simple. He has confirmed His presence to me in the spiritual realm, and that is enough. It is all I need.