Hello Josefina,
Good to have you with us on the forum. I hope you will feel free to post often and lots. In my experience those who post regularly tend to stay with the program and you will find great people here who will support you throughout.
Regarding using other programs alongside BrainEv, the general mantra seems to be not to use other longterm brainwave entrainment programs for the 6 months you are doing the BrainEv program. So listening to a track with subliminal messages, or meditating, or whatever should be OK - provided there is no entrainment to accompany them. Doing one night and one morning sounds like a good idea.
It is common to have greater reactions such as tiredness, falling asleep during sessions, headaches etc. during the first week or two of each level. This is not a given, just that many people report the first week or two of each level pushes them more, and they then settle in after the first few days and usually enjoy the sessions thereafter.
It is interesting how so many of us seem to attach great significance to flashbacks from the past (me included). We all seem to believe that something of great significance is happening. I have read quite a few books now, any I can lay my hands on actually, on entrainment and brainwaves in general.... and just this week I found something very reassuring. First off, and common knowledge, is that theta frequencies, low frequency brainwaves that we experience while dreaming and also during BrainEV - while awake but relaxed, are linked to the subconscious. So flashbacks and memories of the past are a sure sign of your entraining well into lower (theta) frequencies. Well done, that is exactly what is intended. Have a look at the introductory videos and you will see that BrainEv drops deeper and deeper across the levels.
The newsworthy item I discovered this week was that theta brainwaves emanating from the frontal cortex are correlated with the feelings of bliss, peace, expansion etc that meditators rave about. The more frontal theta waves, the greater the feelings of bliss. Interestingly the left hemisphere is associated with positive emotions and the right hemisphere is associated with negative emotions - so, as we entrain from a relaxed alpha mind-state, into a slower, deeper theta mind-state, the brainwaves start to synchronise, involving more and more of the brain (is this whole-brained being?). As we enter theta and the frontal cortex synchronises, we can have either positive or negative flashbacks depending on whether the memory is stored on the left or the right. It is noteworthy that BrainEv-ers on the forum seldom bother to post about fleeting, positive flashbacks, but we all take note of random negative memories that flit across our mental horizon. Really, having flashbacks (whether positive or negative) is just evidence that we are producing good theta waves, and our frontal cortex is currently involved too, which is also good.
Obviously I don't know you, and whether you have things to "get to terms" with or not, I cannot say. However, it is possible that all of us are attaching much significance to something of very little import. When you start to meditate, the general advice is to watch/observe thoughts as they come - and let them go, not getting 'attached' to their content. Based on the neurological data above, frontal cortex theta produces flashbacks. Nothing to get 'attached' to, just another thought to let pass us by as we continue to descend into even lower theta and eventually delta frequencies.
Hope this helps to reassure you. Have a wonderful time with BrainEv, and enjoy the extra happiness. BrainEv did the same for me, I quickly became much more content, resiliant, and emotionally stable. Have a great 6 months, all the best, Pure Bliss
PS Source for above data: The Blissful Brain: Neuroscience and proof of the power of meditation by Dr Shanida Nataraja