I'm not too sure if this is right.

这是否正确，我没有太大把握。

《牛津词典》

Not too sure about that.

我不是很确定那个。

youdao

I'm not too sure of it.

这件事我不太有把握。

youdao

Make sure the soil is not too wet or the seeds could develop poorly.

VOA: special.2009.03.24

I'm not too sure. I think that there's loads of different art colleges,

我不能确定。我想这儿有很多不同的艺术学院，

伦敦的时尚学院 - SpeakingMax英语口语达人

So since that's the easiest scenario, you can probably be sure it's not going to be too frequently that you're just given the energy, right, that might be too easy.

所以既然那是最简单的情况，你可以确信只给你提供能量值的,这种情况不太可能发生太多，对，因为那太简单了。

麻省理工公开课 - 化学原理课程节选

I'm not too sure if Brother Bill is going to be some baggage or not.

NPR: Virginia Democrats Eager for Primary, Election

I'm not too sure whether the market will be willing to lend more to Indonesia at the moment.

CNN: Money & Investing

I'm not too sure why so many people here are giving Hear'Say such a hard time for being manufactured.

BBC: Hear'Say: Your views