Some time I get queries from the readers of Science2.0 blogs and I feel encouraged that my blogs are read across the world. Some time people ask for advice also for their thesis work or literature etc. Through this I wish to answer in general only and specific answers I can give to individuals 

1. How much Ocimum sanctum one can take ? 
 Ocimum sanctum is a sacred plant and traditionally all Hindu families or at least those at place of worship or religious minded families should has this small plant in their house. 
Some time they call it courtyard plant. I have this plant in the hedge of my house and our family never suffered from dengue for the last so many years. Reason is simple . The plants are growing near the source of water or tap in the garden. The smell of the plant does not allow mosquito to flourish and our house is free from mosquito and probably also the disease like dengue does not occur if we prevent the mosquito bite. 
It is customary not to eat Ocimum sanctum and my mother always advised me not to chew Ocimum leaves. 
How to take Ocimum leaves then ? In Hindu temples Tulsi water is given . A small pot of copper contains some tulsi leaves in very small pieces ( one leaf in 10 or more pieces ) which are taken along with around 2 to 3 ml of holy water. We don,t advice to eat it as such in traditional practice. 
Now its left for the modern world to test for its contents and prove if they are useful or not. 

2. Can dudhi help in gaining pregnancy ? 
Dudhi is Croton or Calotropis  hard to say as vernacular names and their meanings vary in region of the country. However one thing is certain. Dudhi contains latex.
Latex is 30 percent triterpenoids. 
As such nobody would recommend to take latex to gain pregnancy on the other hand latex is highly poisonous and can cause blindness if applied to eyes and can cause nausea and ill health if taken by anyone. So don.t ever take latex for any medicine.
Its is for the Ayurvedic doctors  who can prescribe different formulations of latex mixed with some medicines for which I am not aware . Hence my submission is the information provided here on traditional medicine only indicates what is practiced in traditional medicine. It need to be followed in particular manner for particular ailments with concrete advice from practitioners of traditional medicine or Ayurvedic doctors. 
In Japan I found the Institute of Natural Medicine is strongly supported by different medical departments, pharmacists and pharmaceutical companies which make specific formulations and test them properly. Kempo medicine is practiced side by side but under strict supervision of the fully trained doctors. 
So please don't become your own doctor and follow advice of trained doctors only. 
Natural drugs are excellent source of healing only if they are taken with proper guidance and scientific backing.