Beyondblue has information on anxiety which you may find helpful. Look under The Facts at the top of the page and explore. You can also complete the anxiety checklist if this is what is bothering you.
Being able to hear your own heartbeat does not necessarily mean there is something amiss unless your heart is beating very fast or very slow. If you have concerns about your physical health the best person to talk to is your GP.
White Rose mentioned above the resources on the Beyond Blue website that are a wealth of information...always worth a look!
Sometimes our heartbeat can be felt the way you described it. Sometimes after a stressful period or even excitement our heartbeat can be more prominent. Subject to your GP's opinion, this is a very common feeling
