Firstly, u/s measurements of weight are inherently inaccurate, I wouldn't put too much stock in it.

Secondly, 2.1kg @ 34 weeks doesn't make a huge baby! Babies double their weight in the last 10 weeks, so even a baby which is 2.1kg at 30 weeks is only looking to be around 4.2kg, which isn't overly huge. My last one was 4.3kg induced at 37+4 due to extemely high bp. She wasn't overly difficult to birth at all, I think I could birth a baby at least another kilo heavier with no problems .

Thirdly, you eating less won't effect the size of the baby one iota at this point. The baby will just take what it needs to from your muscle mass and cells if you don't give your body the nutrients you need to. You will find yourself malnourished and weak for the birth, increasing your risk for a c/s. You will damage yourself, the baby will be as big as it is fated to be.

With the birth of a big baby, it's not brain surgery....it's nature, just use nature's rules to birth by. Stay upright for the labour to bring bubs down the birth canal, birth with your pelvis open - squatting or on all fours, don't go near lying flat on a bed.....birth upright to use gravity, better still birth in water to cancel out gravity altogether. Don't push too early as you can bruise your cervix and have it swell, which can lead to a c/s, and don't push unless you feel the urged. Pushing because a doctor or nurse tells you to for x number of seconds might sound like a good idea, but they don't know what your body and your baby have planned for the birth - listen to yourself first, your caregivers second.

Best of luck, I hope it all goes well.