pregnant and bleeding

hi. my periods came on d 28th of jan..an ran as a normal periods,it came back on d 28th of feb..jus 4 two days. i had sex like bout 15 days after my periods took a pregncy test 1 week after and it was positive.i started to spot brownish 4 about a week and dan pink finally it start flowing like a normal periods 4 aboiut 3days. did an altrasound and is stated dat am less dan 4 weeks pregnant and everything is ok . but yet still am scared. dis will be my 2nd time tryin to be pregnant. i had a misscariage last yr around dis same time but d experience is different. i jus hope dat am ok .