any more than about 5-7 fish(the smallest commonly available species) in a 5g is pushing it, so yes, you are overstocked.
Tetras and danios should be kept in schools of atleast 5-6 more is better.
You need to identify the sucker fish, some of them grow to 2'+.
the snail problem is caused by excess food, cut down on feedings.
You should be doing water changes(25%min.) with a gravel vacum every week.
Your best solution here is to get atleast a 20g tank and up gravel vacuming, this will keep snail populations low(you can't get rid of them completly) and give you room for a pair of smaller loaches.
Use this site to research future inhabitants and to identify the fish you have, do that and post the list with your next question(s)
Tetras and danios should be kept in schools of atleast 5-6 more is better.
You need to identify the sucker fish, some of them grow to 2'+.
the snail problem is caused by excess food, cut down on feedings.
You should be doing water changes(25%min.) with a gravel vacum every week.
Your best solution here is to get atleast a 20g tank and up gravel vacuming, this will keep snail populations low(you can't get rid of them completly) and give you room for a pair of smaller loaches.
Use this site to research future inhabitants and to identify the fish you have, do that and post the list with your next question(s)