I am not a native speaker (I come from Belarus), where the level of English is not very high. So I was very surprised at my real GRE score.
Quant
Verbal
Total
date taken
The Economist GRE Test
19/40
146
15/40
142
288
10.01.2016
ETS book
test #1, #2
38/50
160
160
03.02.2016
ETS
PowerPrep I
24/40
153
15/40
146
299
09.07.2016
Kaplan
practice test 1
8/20
148
148
07.08.2017
Kaplan
practice test 2
12/20
152
152
07.08.2017
Kaplan
practice test 3
13/20
153
153
08.08.2017
Kaplan
practice test 4
15/20
155
155
08.08.2017
Kaplan
practice test 5
13/20
153
153
10.08.2017
Kaplan
practice test 6
12/20
152
152
12.08.2017
Kaplan
practice test 7
17/20
157
10/20
150
307
12.08.2017
Kaplan
practice test 8
14/20
154
154
12.08.2017
Kaplan
practice test 9
14/20
154
154
13.08.2017
Kaplan
practice test 10
17/20
157
157
13.08.2017
Crunch
Prep
140
141
281
17.08.2017
Kaplan
online free test
25/40
149
19/40
148
297
19.08.2017
ETS
PowerPrep I
24/40
154
154
26.08.2017
ETS
PowerPrep II
22/40
149
19/40
151
300
11.09.2017
Actual GRE
161
145
306
18.09.2017
Time studying: 2 years (with interruptions)
As you can see, none of the mock test, even PowerPrep, predicted the score. I recommend you not to be concerned about any mock test result and just try to do your best at the exam. For that, you need a good rest and clear head during the exam.
Some motivation: only 100 Belorussians took this test, this test is unbelievably challenging for us. I even had to travel to Hungary from Belarus to take this test, since we don't have GRE test centers. Despite all the adversities I had to overcome, I showed a very nice result, so, American people, do not complain, international students have to work thrice as hard as you have. Good luck, have fun