I wouldnt stress about symptoms yet because everyone is different. they may not show up for a few more weeks. some people get sickness right away others not until after weeks 7-8. a Friend of mine is 20 weeks pregnant now and has only had a little tiredness her whole pregnancy. But to answer your question about can you get a positive pregnancy test and have no heartbeat.....Sadly Yes. I recently had a DnC 3 weeks ago due to a missed miscarriage. I had a heart beat at 7 weeks and when i went for my 2nd 13 week ultrasound the baby had no heartbeat. Everything else continued to grow. I had a 13 week placenta producing natural HCG. I had been taking PG test every week since i found out I was pregnant because i had no morning sickness and i had a miscarriage with my last pregnancy. I drove myself crazy but taking PG test is not a guarantee. Dont drive yourself crazy about it. what happened to me is very rare and the chances of it happening to you is less then 3%. Just be happy that your pregnant and enjoy not being sick. I'm sure everything will be fine. lots of baby dust to you.
PS If Baby is measuring normal and no heartbeat yet, dont sweat because they sometimes cant get a heartbeat until 8 weeks. If the baby is measuring small with no heartbeat then worry.
Usually when you take pills to induce your period it's to make sure that you're not pregnant. When did you start taking the pills and when did you take the preg test? Did you already go to the doctor already and weren't able to hear a heartbeat? You usually don't hear a heart beat until a few weeks down the line, between 6-8 weeks, depending on the type of ultrasound machine they use. But from the sounds of it you have a good strong positive. Unfortunately there is no solid symptom that you can link to being pregnant. Some have the same symptoms as when their period is about to come and some have none at all. Before I took a pregnancy test I thought for sure my period was on it's way, but i got a BFP. Keep me posted on your dr.'s visit and good luck to you!