770 on GMAT Prep 3. Should I belive it?

Hey

I have just done GMAT Prep 3 and I scored my all time best Q and my all time best V, yielding a 770(50Q,45V), with only two wrong questions on Q and 4 on verbal.

My CAT scores are:

GMAT Prep 1, Jan 28: 570(40Q,28V) (Cold test)
MGMAT 1, March 24: 600(43Q,31V)
GMAT Prep 2, Apr 25: 680(49Q,34V) I did GMAT Prep 2 after finishing TTP course and doing 7 GMATClub Tests, but with so little verbal prep.
GMAT Prep 3, today: 770(50Q,45V)

I took them in the library, and I had no repeated questions.

Down there you have a picture with my GMATCLub Test scores. On those last 10 days, the day where I did no test, I was redoing incorrect questions. (Q33 is not a real test, i quit at the middle)
By the way, I began to use ErrorLog on Apr 26.

My biggest weakness was SC (I'm lucky, I know) and on those last 10 days since Gprep 2 I have done nearly all Magoosh verbal questions, so I expected that my verbal could improve, but not that much. Yesterday I did a GMATClub Verbal test and scored V25 .
I take GMATClub scores with a grain of salt, as the day before GMAT Prep 2 (Q49) i scored a Q36. GMATClub Tests are the best thing that happened to me during my GMAT Prep, but their scores are very discouraging

I don't know if it is because GMATClub test are really thaaaat hard, but I feel GMAT Prep questions to be easy, so I'm not confident about my scores, I think that maybe I had luck with GMAT Prep 2 and 3 questions and on the real exam I will get harder questions...

Evidently I'm very happy with that score, but I'm not sure whether I should belive that I already have a high level.
I know that I'm not on the 770 level, or at least I think that I'm not, I mean 90 points in 10 days is not reasonable, my concern is if I'm really above 700, as I see a lot of people scpring so high on the practice tests and then with poor scores on the real day.

The thing is: I have the exam scheduled for May 27 (in 23 days), but there is a free spot on May 8, so in case it went wrong, I could still take it the 27th (+16 days gap).

I'm considering seriously to do the exam the 8th because I feel that maybe I'm in good shape, I've been studying all day for 40 days now and I think that at this point I can improve in some areas (combinatorics ) but I also think that maybe I will forget some things if I wait more days, as I have seen a lot of histories of people whose score keeps decreasing instead of increasing.

What do you think abut my scores? And about the date?

BTW my target is +700, the more the better, but the deadline is May 30.