It is still early to be feeling your baby move.  Some women can, but it could just be the muscles stretching etc.

I doubt very much you are feeling your baby's heartbeat.  It would more than likely be your own coming through the aorta down through your stomach. 

Generally, movement by baby is felt sooner by experienced mothers compared to first time mothers.

At 13 weeks, it is possible that you're feeling flutters, which feels like gas bubbles. But as far as heartbeat, you woudn't feel it. Heatbeat can't actually be felt just by putting your hand on your belly. As your baby gets bigger, you may feel rhythmic thumping on your belly, but that is a hiccup. Babies in the belly can hiccup, and sometimes pretty violently. You'll know it's a hiccup because it's slow - much slower than an adult heartbeat which is usually around 70 beats a minute (when resting). Babies heartbeat go up to 150 beats a minute, and this is only known to moms because of ultrasounds and dopplers at the doctor's office.

With my first, I felt flutters at about 16 weeks.  With my twins, I felt movement at 12 weeks.

i didnt feel definite movements til around week 16 and i got my first big kick on mothers day last year :)

if yo're feeling the "heartbeat" while lying down, it's probably your aorta pushing your organs up a little with the pumping of blood. i know when i laid down while pregnant i could feel this kind of beating, but it was just my own heartbeat lol. the volume of blood you have increased when you are pregnant and your heartrate will increase also.

At 13 weeks you are most likely feeling bubbles of gas moving due to the pressure of the baby. Here's some info...

• Your infant is about 2.91 inches (7.4cm) and weighs around 0.81 ounce (23gm) - This is about the same weight as 4 quarters.
• If you could peek in again you may spot your baby as he begins to practice inhaling and exhaling movements
• Eyes and ears continue to move and develop
• Baby's neck is getting longer, and the chin no longer is resting on his chest
• Her hands are becoming more functional - Your baby may find it comforting to start playing with her fist.
• At this point all nourishment is received from the placenta
• On your next doctor visit you should be able to hear heartbeat with a Doppler by now - (Don't worry though if you can't, the heartbeat can be confirmed through U/S). Your baby's heartbeat is much rapider than your own and may remind you of the race towards birth that he is running!

I could feel flutters from around 14-15 weeks. I was only 48kgs when i fell pregnant, so i was thin. I felt the first big kick when i was 19weeks and 5days and i could even see it aswell.

I couldnt feel a heart beat, Im 36weeks pregnant now and still cant feel a heartbeat.

Dannii xxo

I was skinny when I was first pregg. with Jedd. The nurses told me that it is normal to feel the baby up to as early as 12 weeks for skinny people...LOL One nurse told me it wasn't possible and I just had gas...but I never farted..LOL so I knew it wasn't gas...

I s poke with another nurse about the baby's movements when I was working out and she asked my weight When I told her she told me I was feeling movemtn sure enough...

It is early at 13 weeks to feel anything, but some women can.  I know I could, and it felt like little tickles inside.  If you sit really still and focus on your uterus, if you feel like a light brushing, more then likely it's the baby moving, though it would be easily to feel for another few weeks or so.  You won't actually feel the heart beat in the baby at anytime, only be able to hear it via doppler.  You will however be able to notice your heart beating more due to increase in fluid volume.  Hope that helps...And congratulations!