Is it possible to have strong prgncy symptoms sore breasts, cramps/twinges, lower backache, bloating/gas, vivid dreams - before a positive test?

Not likely: Normally classic pregnancy symptoms don't begin until you have missed a period. Many don't begin until well after that time (when a + pregnancy test is likely).

You've proven it is: The real question is whether they necessarily mean you are pregnant. And that it can't. Those signs can all mean a variety of things or nothing at all. A missed period followed a few days later by a positive test is the key. Be patient. Best wishes!