I missed period for 3 days but after it cames. ma breast has shooting milk. should i be pregnant?

When in doubt: just check pregnancy test. And if you are late and first pregnancy test was negative, check it again in 1 week. If you have two negatives then you can rest assured. Then see if your periods will return to normal. If it does not in 3-4 months, you may need to visit GYN or family physician. The lactation is certainly worrisome that you may have been pregnant then miscarriage which explains bleed