As Per Sec. 2(45) of the CGST Act, 2017 E-commerce operator means any person who owns, operates or Manages digital or electronic facility or platform for electronic commerce. Any Person who is supplying Goods/Services on his account, however would not be considered as E-commerce operator.
As you can see E-commerce operator is only a facilitator. If you buy and sell products, even through your portal, that operation does not come under E-commerce operator,