No symptoms on second pregnancy???

My first pregnancy, I had pretty much all the symptoms you can get, nausea, heartburns, extremely sensitives breasts (especially the nipples) and so on. Sadly, at 7 weeks I had a miscarriage. On a much happier note, I found out I was pregnant again 3 days ago BUT this time, I have no symptoms what so ever...Except that I cry for pretty much everything and nothing. At first, I thought that maybe it was extreme PMS-ing...If it was not for all those dreams I was having about positive pregnancy tests, I would have never done one. Is this normal?? Can your symptoms vary completely from one pregnancy to another?