Given the data you provided, if the spotting does not re-appear, if everything seems normal and it turns out to be that you have a missed period, you should wait until 5-7 days after the first day of a missed period and then do the home pregnancy test.
If this does not turn out to be a pregnancy, spotting a week before the start of your period, might mean that you had a slight sexual hormones imbalance (the progesterone had a fast drop before the cycle, which might end up with spotting a week before a period). This should not be serious if it happened only once and if it did not lead to other, more serious consequences. You should take 1 gram of vitamin C daily, as well as a lot of fluids, cranberry juice and parsley tea for the bladder infection. If the urinary tract infection (UTI) does not seem to go away, you should do a urine culture with antibiogram, so that your doctor could prescribe an appropriate uroantiseptic (antibiotic). It might be recommended that you see a gynecologist immediately, if things get worse.