Hi and welcome here,
If your girl is healthy and strong then I see no reason why she shouldn't have a normal birth and produce healthy kittens. I had a girl years ago that started calling at 4 months old. I bred her at 10 months as she was very healthy and a good size. She went on to produce 8 kittens without any problems at all.
I'm really not sure why some breeders insist on mating queens after 2 or 3 calls or they will 'be in danger'. As long as you keep a close eye on their health and regularly check their temperature, look out for signs of lethargy/decreased appetite etc.. whilst they are in heat, then letting them have more than 3 heat cycles (if they are still relatively young) shouldn't be a concern as long as their health is closely monitored and/or regular vet visits are taken to check for infections.
Good luck