Too much or very much are common. In negative contexts, they just mean much.
- I don't have enough time.
You're having Pop-Tarts for dinner.
- I don't have much time.
This might mean: I probably have enough time, but it's going to be close.
Or it might mean: I am about to try to get you to cook dinner tonight.
- I don't have very much time.
- I don't have a whole lot of time.
- I don't have too much time.
All virtually identical to 2. If there's a difference, it's that these are logically a bit weaker. In 5 the literal meaning is that I do not have an excessive amount of time—not much of a statement.
The combination of negation + intensifier makes the meaning subtle. In a positive context, things are easier. You can't use much by itself (I have much time is wrong) and too much literally means an excessive amount (I have too much time to myself is fine).