I planted a seed I got from a grocery store lemon about 4 years ago and this is my tree today. It's not very big, and the branching is kind of weird. I don't mind if it produces fruit or not, I just hope it will grow and do well. Recently, all of the leaves fell off but new growth appeared. I don't have much experience gardening, so I hope someone can let me know if it's healthy and needs other care (like pruning maybe?). Please help!! Many thanks in advance!!
Looking at this picture, to me it seems it may need more sunlight. It looks very "leggy", which indicates it's stretching to catch the light and wants more sun. But I'm impressed it's grown from seed that well! Also, you may want to rotate the pot, so it's leaning opposite to the light source. This will help it grow stronger. If you do give it more light, be sure to incrementally introduce it to the new location. Sudden changes can upset the trees system. The ideal light for citrus trees are partial shade to full sun, meaning sun hits the leaves directly for a few hours a day at least. Keep in mind, if you give it more sun, it may need to be watered more often, and will also need nutrients to help it keep up with the new growth. It may take a couple of years for it to be bushier, but it should help it liven up. It may survive in the shade just fine, but it's not going to really grow much or look very attractive. By the way, I would not prune this right now. Cutting it will make it put resources into closing the wound, instead of growing it. It doesn't look like it has many resources to spare right now.
I want to add a few things that I think can further help you. What Fleur de Vie said was super good advice.
For the lighting: I would consider getting a grow light of some kind. This makes a good example --> Grow-light. I got these and they work pretty good. But a full spectrum is slightly better than blue/red light this one is. Reason for getting something like this would to get better light for the plant. Like Fleur de Vie said the plant is leaning towards the window for more light. If you give it more light above that should stop the leaning. Don't need to keep the light super close but a good 2 ft I think would be good. Also like he/she said mind the change, could shock the plant. I don't know if it will have a huge affect on watering times.
Fertilizing: While I don't think the plant needs it right now, but I would consider getting a fertilizer, This is a good example --> Jacks fertilizer. It is kinda pricey compared to cheaper stuff but will last a Long time. Only reason for that would be if the plant uses up all the fertilizer in the soil. By uses the fertilizer it should grow a lot better for you.