Medical Mystery

So, after having my first daughter i've been dealing w/ this strange sort of sternum pressure which makes me pretty weak . I've had clear upper gi's and blood work done and no Dr. Can explain it. I've just let that issue run off my back and decided if my doc's don't think it worth it to research further, I shouldn't worry about it.
Then w/ in the last year i've started to get some heart pains (sharp) sporatically and vertigo which, again, i've clear blood work and an mri for.
Finally, at my recent check-up the Dr. I saw said my lungs were wheezing and all of the above are symptoms of athesma. Though, i've never really had any breathing difficulties. Does this sound correct.
And if it is correct and that's the actual diagnosis, i'm so annoyed that i've been having these issues and scared to death something may be really wrong or going on inside me. Why was this not put together and discovered sooner. I mean, in the part 5 years these symptoms have been occurring each Dr. I've seen has listened to my heart and lungs.
I mean, it seems to have been an easy diagnosis...Did I just slip through the cracks here? Or was I previously dealing w/ docs that don't have time for me and just wrote me off has bing a hyperchondriac?