I'll just mention some common maintenance issue that you might want to think about. Since we can't see the plant or the environment, you're going to have to be your own plant doctor. You can do it!

Citrus thrive in high light situations, so you might want to make sure that your light source is strong enough.

The potting medium should be very coarse and fast draining, meaning that it will be composed mostly of large particles. That type of medium encourages the development of new roots at all times and also makes it very difficult to over water a plant.

The container should be large enough so that the roots have some wiggle room but not so big that the plant might sit in stagnant soil for a couple of years before the roots start to fill it. Over-potting can cause real problems for plants, especially if the mix is slow to drain.

Also, container watering can be a puzzle to many people. You see, all of our plants need to be drenched thoroughly when it's time to water. We WANT water to drain out of the bottom, lots of it....all of the excess should evacuate the pot fairly rapidly in a good medium. Then, it's up to us to decide how long we should wait until the next time we water. Use your aqua globe for ornamental use only. It can't deliver the right amount of water.

So, how often to water? Citrus like to dry out somewhat between drenches, but never allowed to become bone dry. Your fingers should be the judge. Frequency will depend upon the temperature and humidity levels of the room, light intensity and duration, type and size of container, type of potting medium, size of the plant, time of year, and other factors. Your citrus may need to be watered thoroughly (in your warm and dry home) every week, OR it might not need it but once a month!

If you have never fertilized your plant, then I promise you that it is absolutely 'starving' to death. Containerized plants require regular applications of fertilizer in order to thrive and survive. At this point, ANY regular soluble houseplant food would be perfectly fine, mixed at half the rate on the directions (or less). If your potting medium is a typical peaty mix, fertilize every fourth watering. If you've come up with porous, well-aerated medium, you can fertilize every other time. Always use 1/2 to 1/4 rates.