As a matter of fact, The citrus fruits are a major exception to the rule about seedlings coming true. The reason for this is that the seeds are special and generally contain parthenocarpic embryos with, or instead of, pollenation derived embryos. For this reason, you can often raise 2-4 seedlings from a single seed of these plants. It is, in fact, hard to get pollenation derived seedlings at all in many cases.

However:

Citrus plants grown from seed go through an extended juvenile stage, and may take many years to reach adult stage and bear flowers and fruit. For this reason, grafting is most often used to bypass this juvenile stage.

George

from seed Rarely do they produce quality fruit. Have had good luck using 0.1% IBA (rooting hormone) to produce rooted cuting. Grafting is the other method & use your seedlings as root stock....

If you can wait I think your tree will bear good fruit. Your tree will almost certainly grow to a standard size lemon tree which may overcome your space. With space in mind you may wish to grow it as a multi-trunk that will be easier to keep in the space available. Al