Congrats on using the pill and condoms (even if you have slipped up) that's why using two kinds of birth control is best - if one fails (ie condom breaks/falls off) you've still got back-up.
Ok your symptoms could be pregnancy symptoms but I really doubt it, if you have been taking your pills correctly.
If you have serious concerns see your doctor who can check for you and also maybe switch to a different brand (although only 4 months you may well just be adjusting to it).
I couldn't get on with the "normal pill" and had to use the "mini pill" instead which has to be taken every single day with no dummy pills.