Definitely sounds like round ligament pain to me!
It's completely normal as they are one of the major sets of ligaments that work to support the ever expanding uterus! Some women experience round ligament symptoms in the early first-trimester, while others don't start feeling it until later in pregnancy (or sometimes not at all).
The good thing is that there are a couple of things you can do to help relieve the discomfort. The first is to massage your round ligaments every day.
To locate them - start with one finger on your belly button and follow a line out 45 degrees downwards and out towards your side. Then take your other hand and start on the top of your ASIS (the bone you can feel in front at the top of your pelvis, on both sides) and follow a line downwards and in towards the center of your body. The point where the two lines intersect is approximately where the center of your round ligament will be. Massage around in that general area and you will most likely feel something tight, tender, and possibly rope-like. That is your round ligament!
Find the round ligaments on both sides. Often times, one side will feel much tighter than the other. Massage the tight round ligament with your fingers moving in a gentle circular motion. After awhile, you should feel the ligament start to relax a bit. You may also want to spend some time massaging the opposite side, especially if it also feels tight. If you do this every day, it can really help!
If you find that the self massage isn't quite enough, you can find a chiropractor trained and certified in the Webster Technique. It's specific for pregnancy, and focuses on balancing out and releasing the round ligaments along with the pelvis and sacrum. The only time I've been experiencing round ligament and low back pain is when I've gone more than a week between getting adjusted and having my round ligaments "released". It really does make a huge difference!