The use and difference between んじゃないかと思った　and　んじゃないかと思う


I am having problem understanding the difference between んじゃないかと思った and
んじゃないかと思う。

As for んじゃないかと思った, I found the following examples:"忘れているんじゃないかと思った" and
"間に合わないんじゃないかと思った"。

Moreover, in regards to んじゃないかと思う, I found these two examples:
"断れたんじゃなかったかと思いますが" and "慎重なんじゃないかと思う".

To be honest, i found myself unable to translate these sentences and thus
understanding the grammar behind them. Could you explain them to me?

I know かと思った that expresses that one thought/ was afraid that something would
happen, but eventually it did not. However, despite being apparently similar
they seem to hold a different meaning and usage.




思った is past tense, whereas 思う is present tense. 思う would be used when
communicating what you currently think/feel, whereas 思った would convey what you
thought at the time of the subject in question. Expressing fears that turned
out to be unfounded is indeed a common use of 思った, but it's hardly limited to
that.

