If you got your period a few weeks ago, then you may have another month until you get your period again.
However, the second bleeding you had, was it extremely light? There is such a thing as implantation bleeding, which is around the time you would have conceived a baby.
If you're concerned about pregnancy, then I would suggest that you get a pregnancy test. Wait until you feel you've missed a period (or when you should have gotten it) and then take it. That's what I would think.
As for spermicide, you said it yourself, it's not 100% thing. None of the contraceptions are... however, spermicide doesn't have as high a success rate as something like a condom. If you are planning on using spermicide again, I would consider at least to pair that up with withdrawal... though a condom (or birth control) would be better.