Jake is, he is growing out of it though and can tolerate dairy now however if he has too much his poos become really runny again...
TBH I would be getting a referral to a paed, mine told me the tests most GPs do are actually misleading and can diagnose a lactose intolerance when it may not be.... not sure what tests your GP did of course.
Its actually easy for FF babies as you can just give them lactose free formula and avoid dairy when introducing solids... be aware if you are planning on using jar foods there is A LOT of the stage 2/3 jars that have dairy in them so you will need to read all the ingredients.
Jakes was caused by a virus affecting his tummy and is finally coming right... true lactose intollerance isnt so common so hopefully it wont be an issue for the future