Citrus plants grown from seed are often reluctant to flower and fruit - commercially-grown citrus is nearly always grown from a good, known variety grafted onto a vigorous, seed-grown rootstock. Don’t let that spoil your fun though; a pot-grown lemon tree is an attractive plant even if it never produces anything but leaves.
Growing it in a pot will curb the growth somewhat and it will need careful feeding and very occasional repotting (they don’t respond well to root disturbance or pots that are too large) in order to stay healthy. In twenty years or so, it may be big enough that you’ll need a trolley to move it about, but that’s a long way in the future.
In the winter, protect it from frost (if you have such things in your locality) and don’t overdo the watering/feeding - in the spring and summer, water more freely and feed it occasionally with a balanced houseplant food. They like slightly acidic soil, so if your tap water is hard, you might want to collect rainwater for your tree.
It will probably start to develop some really wicked thorns about now and it may also produce some unruly growth in the form of ‘water sprouts’ - soft, sappy, fast-growing shoots - these (and any other unruly growth) can be trimmed back or pruned, but that won’t stop it from producing another shoot in pretty much the same place.
It may produce flowers for you when it is five years old, but it is far from being a certainty.
Did something similar with grapefruit seeds, which I found already sprouted in a grapefruit I was preparing to eat. After the 3 plants I eventually got reached about 10" tall[in just under a year] I got the bright idea of making them bonsai specimens. After wiring the branches and caring for them, they started to flower at the height of about 15". One of the most powerful and pervasive scents I ever smelled, their odor filled up whatever room I temporarily put them in. Perhaps the techniques[wiring, root pruning, keeping in small containers, skimping on fertilizer, etc.] to train bonsai caused them to flower ahead of schedule. You may wish to experiment with a branch or two, to see what happens. Keep your eye out for citrus scale, it was a real bear to get rid of.
Aaaaaaauuuuuuuggggh!May the ghost of Burl Ives echo your footsteps forever! May “Having My Baby” haunt your most serene moments. May you never go to church without "God damn the pusherdogging your every hymn. If you weren’t named after a valiant mouse, I’d whisper to my close friend Og about you. You’re lucky, pal. Very fortunate, indeed. :wally I’m glad your mother isn’t here. She’d be disappointed in you. Or maybe not.