You may be experiencing Postpartum alopecia.
Some women experience (PA) after having a baby.
However it is totally normal. During pregnancy the hair stays longer (anagen stage),then after childbirth the hair enters into the telogen phase.
The loss of hair is the result of the body hormonal balance returning to it's previous state.
What type of hair care products are you using?
You should also google postpartum alopecia for more information.
If you think this is not the case,try getting some products to treat the hair loss,such as thickening agent.
Some shampoos and conditioners contain this.