Citrus trees need good drainage. I have grown mine from cuttings since I don't really want to wait 5-7 years for fruit and some trees will just be better than others. Even from a cutting, a six inch cutting will only go into a 6 inch pot. The soil must be free draining, but the bottle shard is probably not a great idea. One, if you forget it is there it can be dangerous when it comes time to repot. I stopped using clay shards a long time ago, because it doesn't always help drainage unless it is properly placed. A better choice will be a pot with a lot of holes in the bottom and on the sides.
I use pure cinder for my potted citrus trees once they get about 3 ft tall. Cinder and a 20 inch pot is very heavy so, the pot is only tilted to make sure it is not rooting and I provide the tree with all of the nutrients it needs through slow release fertilizers every three months or so. I have trees in 20 inch pots that are over 18 years old and they have not been repotted, ever. For younger trees, they need more water, so I put them in my usual 50/50 peat moss and perlite with citrus food every three months or so. I have a dry mix because of the way I water, my pots can be watered every 1-4 days depending on the time of the year. If I use a mix with more peat moss, many of the plants will drown in the rainy season, so I go with a dry mix year round.
I think you should take your seedling and repot it in a six inch pot with potting soil like miracle grow and add additional coarse sand or perlite to make the mix very light and free draining. It should be dry in a day or two, if it holds water longer than that it is probably in the house and not getting enough air and light. Also ditch the saucer, saucers will just cause the plant to die if you don't keep them emptied of water. Depending on the type of citrus you have they have different cold tolerances. None of them really can handle freezing. As soon as you can harden it off to go outside.
Citrus trees have growing and dormant seasons. I don't know where you live, but right now in the tropics the citrus trees are flowering and a month ago they put on new growth, they will continue to leaf out until the fruit start to appear, then the growth pretty much halts and the fruit will slowly mature over the summer until they are ready in the fall.
You need to feed your seedling with citrus food every three months or miracle grow for acid loving plants every two weeks while it is in a growth phase. Feed citrus food to a mature tree just before they leaf out and again when the fruit start to mature.
Mature trees in the ground with good drainage only need to be deep watered once a week, they like to dry out a bit between. In pots, they need to be watered more often but can handle a dry spell better than too much water.
Happy gardening in Hawaii. Gardens are where people grow.