I'm considering to upgrade From my DSLR camera?

I have a Nikon D3100 and was considering to buy a new camera in exchange but i do not have sufficient money to purchase a higher level DSLR so i was thinking to go with D3200 or D5100, What do you suggest?
i mean the D3100 does lack Kelvin White balance and i rotating LCD. I was looking for a camera that has the DOF option and the Off camera flash option.

I'm not sure whether or not the D3100 has a DOF preview, but if you mean depth-of-field control, any DSLR will do that.

There are any number of flash units that can be slaved to the D3100's on-board flashgun.

You should be using the viewfinder, not the screen - the handful of times you'll use a rotating screen is unlikely to justify the expense.

Colour temperature is measured in Kelvin, but white balance is as much an aesthetic issue as anything else.

You're trying to justify a more expensive camera because your Nikon isn't doing what you want it to - I'd suggest learning to get the best out of the kit you have.

The Nikon D3000 and D5000 series cameras both lack depth of field preview… You'll find it on the D7000 series though, that's my only real gripe with my D5100…

I prefer to have the depth of field preview as an option on my cameras… That's one of the main reasons I reckon Pentax are better value for money than Nikon for a beginner… To be fair though I really don't use it that much, just now and again for macro work.

While the D3100 doesn't allow you to enter a specific Kelvin value for white balance, it does have a rather extensive list of color temperatures, see page 88 of your manual. The D3200 and D5100 have the same white balance options.

For communication purposes a "rotating LCD" does not communicate as well as a flip screen or an articulated screen. The D5100 does have a fully articulated screen and the D3200 does not.

For off camera flash option, you can use the SU-800, see page 173 of your manual.

Other than the fully articulated screen on the D5100, I don't see an upgrade.

You might want to look into the Sony Alpha-SLT-A58 or the Pentax K-500.

I'd buy new glass instead. And books on digital photography.