Is MEPS trustworthy with the ASVAB?

I took the ASVAB and passed, but my scores weren't high enough for the MOS I wanted (medic specialist and cryptology). I took it again and I scored a 14 and I was shocked because I did study really hard. The third time I took it I scored 23 and I was more shocked because I had spent 4 months studying plus I got a tutor. I took tests online that simulate the asvab and I did good and I did super good in all of my tutor practice tests. Everyone I've met who passed the ASVAB and took it again 2 and 3 times to score higher for a specific MOS NEVER again passed the test.

I've met people who scored 50 and above the first time and then retested and scored a 7!! I just cant believe someone can possibly score that low in a 3 hour test after they had score high the first time.

I bought the asvab flash cards, the asvab for dummies and the kaplan study guide and studied them for months.

Does someone knows if MEPS makes the people who took the ASVAB again after they had passed fail the test? I am just wondering since I studied so hard plus I am good at word knowledge, general science and arithmetics.

Can someone explain me why does this happen and if it has happened to you? Did you finally passed?

Is this happening because MEPS considers it cheating because we shouldn't retest to score higher for a specific MOS?

Thanks!!