You make it sound so easy. Regulus and TB both have abilities that can slow you down. If he bought a +speed item what makes you think that the Sedna won't do the same?
you make it sound so hard. you see both of them before they can do anything. we're talking about early game here? permafrost lvl1 just slows for 3%, that's not a big deal. also he has to get near you.
and for regulus...well just fucking run away, he won't be able to shoot if he's not in range...and we're still talking about early game here. he will only have lvl 1 range. and even if he gets in range, maim lvl 1 will slow for just 5%. so there will be 8% max until lvl 5...wand of speed negates and still improves.
so if you don't let them get near you, there might be sedna cause she is faster, but she won't be able to kill you alone if you run instantly.
until they're lvl 5 you should notice they are focusing on you, so stack on speed and hp (and skill shield).
they won't continue ganging on you if you proceed like i already posted or they will be wasting time while your enemies will level up, capture the flags -> especially gold flag <- and buy currency, which your team will get earlier as your war rank will be higher, so there shouldn't be a problem with gold neither!
so...yes it's your fault, you're not innocent, but it's your team's fault too, because they didn't help. at the end of the day, you were the worse team 