Mummyfor3, thanks for your reply!
I'm not offended at all as I'm totally new to babies and am indeed taking many things too seriously just because i think it's better to be a bit overcautious than undercautious.
At first i also thought that it's just the way it is supposed to be (especially because everybody around kept saying so, even those who knew nothing about babies themselves and were just thinking stereotypes like "all babies cry, all babies fuss, etc"), but then i started noticing that sometimes my baby feels much better, so started experimenting with excluding/reintroducing foods (she was a week or two short of 3 months old then) and saw a definite link between fruits/sugary foods and my baby's state. So, I excluded those and she got much better but still was not feeling as good as it could be (and by then i knew she could be feeling miles better and be much less fretful and whiny). Then tried excluding dairy and again, she got better, but not that much, although i think it could have been because i kept trying to reintroduce some other foods or trying new foods at the same time), then i excluded gluten (she was around 4 months old) and stopped trying to reintroduce anything for a while and then finally she got to a much more stable state. And since then whenever I tried eating anything from that list, she would get worse.
I admit that it all could have been a coincidence during her early months, because her body could have been getting mature just at the right times to make it look as though she was getting better because of the changes I was making (although i still feel that there were too many an occasion of her getting worse in about half a day after i eat a certain food to say it was a pure coincidence). And it does correspond to what you mentioned as the age when their bowels become mature.
But there were a number of occasions after that as well with cheese, corn and champaigne among the latest.
And now, when she's 7 months old and feeling well most of the time, i can easily see when she becomes unwell and i doubt it can be caused by immaturity of her body anymore (although her body is still immature, i guess it's not immature to that extent).
Although as I said I know nothing about babies and can be wrong about everything.
A month a half ago i tried reintroducing dairy, but got a strong reaction, so had to exclude it again.
I BFed her exclusively up to 6 months, then tried solids, introducing them slowly, one in 3-4 days, and getting same reaction to a number of them.
I don't have any true allergy, just an intolerance to chocolate and oranges, and a reaction to wasp's venom (not sure how strong it is but it required a prompt trip to A&E when I got stung), so doubt I can be called allergic.
But at the end of the day, I don't regret doing all that, even if it was a silly thing to do, because I don't want to think later that she was suffering just because I didn't want to make a change for her.
And now i can't force myself to try eating all those things again just because I don't want her to suffer! That's why I'm looking for a way to either confirm or disproof my fears without a need for her to suffer much again.
And yes, I know that some people can have lucrative motivations prevailing, thanks for reminding me about that!
I will be only glad to have someone disproof my fears! But only if my baby is feeling well.
Do you think it can still be caused by immaturity of her bowel? And what shall I do when she reacts to solids? My GP told me to continue giving her food that caused reaction no matter what, which sounds a bit strange to me, but I don't know about possible reasons behind such advice.