I try my hardest to get them in a straight line
There's your problem right there. That is EXACTLY what the pikeman wants you to try. It just gives him a perfect line up to pin you down while his ally swings away.
You can't fight a pike/LS like you would a 2Her (i.e getting the two between each other with the one that came at you first in front). Footwork is EXTREMELY important when fighting a pikeman, it's just not the same footwork you would use against a 2H + 2H combo.
What you need to do is get past the random melee-er, and get the pikeman between you and him. It requires playing very defensively, as far as blocks goes, while using very aggressive footwork. to get past the melee-er without getting stabbed. I wouldn't even try and attack until you've gotten past the melee-er.
If you can get them separated long enough for one of them to attack without the other being able to help, you can often use this as an opportunity to get into melee range of the pikeman, and get around him.
Just a tip, pikeman don't like to wiggle to the right. It works fine, but it just feels really weird. So if you can, try and circle around to your right when getting past the melee-er, so he's in the way of their wiggle. This is by no means a 100% guarantee it will work, but it's a much safer bet than trying to go left.