I would prefer a lad to have had fewer girlfriends as it would make me feel more special. It would also show that the lad doesn't just go with any girl he meets.
I would def prefer a lad to have had a couple of special, meaningful relationships before me than say someone who went with any girl, hardlg got to know her, shagged her etc and moved on.
And btw to the OP I have never had a 'proper' boyfriend who I have been in love with or anything so don't feel unhappy or left out. I am 16 and this is unusual in my friendship circle as many of my friends have relationships. Someone will come along, it just might take time to find someone who is special.
Whatever you do, do not get upset over it. Keep occupied in over areas of your life - friends, family, school, hobbies etc and a girl will probably appear when you least expect it.