Who decides who gets to heaven, purgatory or where ever, God? the Pope? the Church? a lottery? or the person them self?
Jo gave you an answer as well, so I'll try to elaborate in another direction.
We only know in the case of canonized saints because the Church, after rigorous examination of the record of their lives and the miracles they performed after death, guided by the Holy Ghost, reveals their status to us. About others, we are asked to hope and pray. It is, of course, Christ who decides in His sovereign particular judgement.
The Church teaches that one can pray for the soul of anyone dead, but the prayer is efficacious only is the person is in purgatory, where our prayer works to speed (*) his release. If he is is hell, our prayer cannot remove him, and if he is in heaven, there is nothing better for him that our prayers could add. Likewise, one can pray for the intercession of anyone, but the prayer is only efficacious if the person whose intercession is asked is in heaven, and we only know with certainty that the saints are in heaven.
Connected to this is the issue of the theological virtue of hope (1 Corinthians 13:13, 1 Thesssalonians 5:8, Ephesians 1:18). On the two sides of hope are the sin of presumption of one's eventual salvation (Luke 18:10-14) and the sin of despair of it (Matthew 27:3-5). It is not a healthy preoccupation to seek a sense of certainty about the condition of the soul of most departed, and the Church canonizes saints not in order to keep inventory of the saved souls, but to nurture hope.
(*) "Speed" is merely a figure of speech here, as following death the soul exits the temporal realm and so the measure of time cannot be meaningfully applied to the process of purification.
Sounds more like a glaring example of the "sin of presumption."
So only saints are in Heaven?