We have most of what you think we don't have. It's just that procuring everything needed takes time and money. And the difference between India and China is, the Chinese started procuring advanced stuff when their economy was about our size today. Purely when comparing economies, we are in a much better place than they were when they were our size.
In fact, they didn't have anything that could actually threaten us at that point in time. However in just 3 years we will have everything we need in order to almost guarantee superiority over them with just our current levels of spending.
DRDO has been experiencing reverse brain drain since a decade, which is why they are delivering now.