I think the first trimester is so commonly portrayed as women throwing up every morning, craving pickles and having sore breasts, that most women don't realise that this is so not the case with every pregnancy. In fact I think this is one of the most misconstrued parts of pregnancy.
When we find out we're pregnant, we start waiting for the morning sickness or sore boobs to kick in and get worried when they don't, that it's not a 'normal' pregnancy. I wish more media actually portrayed the first trimester in different ways so women wouldn't expect to be hugging the toilet and feeling sick every time a smell goes past!
With my first, the only real symptom I had was exhaustion. No morning sickness, sore boobs, vomiting, cravings. Nothing. I also had back pain from about 8 weeks, and was in maternity clothes at 10 weeks due to hating waist bands on jeans. I then only had nausea on the tram. I bet no one else on here could say that but it was 'normal' for me!
With this pregnancy so far, I've had on and off nausea and diarrhoea, pretty bad cramps from week 4-5.5, on and off tiredness, and on and off erect sore nipples. Some hours I feel okay, others I feel like I died and have been microwaved back to life. From my positive pregnancy test I've also had hip pain and my moods are so awful that I'm severely angry one minute and sobbing like the world is ending the next.
I think that as long as you're not getting any warning signs like bleeding, severe cramps or passing out, it's normal for you to have no symptoms or symptoms that come and go. I've seen so many threads on here asking the exact same question, and I think it's more normal than we expect it to be.
From what I've seen, it's more common for women in the first trimester to have no morning sickness or symptoms that come and go than to have constant ones.
If you are worried though, you could always book a private early scan from 6+ weeks. I had one on Saturday due to having awful cramps and was worried it was an ectopic (despite no history of one). Saw a blob and a heartbeat and have now since relaxed that the cramps were just part of my symptoms this time. Now they've stopped!
She stopped trying and started planning her wedding and then fell pregnant with me a few months later. 
