There is a small mosque beside my house. The problem is that no one prays in this mosque except me and one other person.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Praying in congregation is one of the best acts and it helps the person perform all prayers at their prescribed fixed time.
So, if you can pray in a big mosque where there is a large number of Muslims, then it is better for you than praying in a small mosque with only one person, although praying there is sufficient and entitles the person to the reward of praying in congregation.

Ubay Ibn Ka’b narrated: “The Prophet once prayed the Fajr (dawn prayer) then said: “Did such (he named a person) attend the prayer?” They said: “No.” He said: “And did such (another person) attend?” They said: “No.” Then the Prophet said: “Indeed these two prayers (i.e. Fajr and ‘Ishaa’) are among the most unpleasant prayers for hypocrites and if they knew what there is in them (their reward), they would come to them even if they had to crawl. The first row in prayer is similar to that of angels and if you know its great profit you will hasten for it. The prayer of the man with another man is better than his prayer alone and his prayer with two is better than his prayer with one and the more numerous the more Allah likes it.” [Ahmad and others]

From this Hadeeth you know that praying in a mosque that has a larger group is better than praying in a smaller one. So, you should pray in the mosque with the larger number if you can. Otherwise continue praying in the mosque you mentioned and try to get more people to pray there.

Allah knows best.