My 7month LhasaApso isbleeding, is this normal at such a young age?

Yes many smaller breeds will come into season/heat at an early age.

Keep her away from all other dogs for a period of 3 weeks.
Generally they will bleed for around 1 week but their actual heat lasts another 2 weeks after the bleeding stops.

I would suggest putting an old sheet over any furniture or bedding she usually sleeps on as it will get messy.

Keep lawns cut short as well, dogs in heat are more prone to infections picked up from grass, so the shorter the grass, the less chance of picking anything up when the dog squats to urinate.

Once her heat is over you can book her in to get her spayed.

Tactful as usual :)