Tri / Triathlon / Triathlons - do they float your boat?

I not training for sprint distance tris, it's coss training for a marathon I'm doing in September, if I was I'd be training as I would for a 5k I guess, lots of speed work, running up to 10k ish for endurance and a decent amount of strength and conditioning.

Which is essentially what I'm doing for the marathon except my long weekend runs are a lot longer and I'm pretty much ignoring the bike at the moment.

Weekly raining schedule is something like this.
Monday weight training am/pool session pm
Tuesday run speed session
Wednesday weight training session am/ run tempo session pm
Thursday bike speed session (usually a 10 mile tt)
Friday rest
Saturday long run
Sunday long open water swim

Every week day I commute about 5 miles each way by bike.

Think ive been training too hard and not resting enough.. been feeling dog tired at work, power is down on the bike.

Not sure if I should just keep on and hope I condition to regime or if I would be better dialing it back.

How did you find the right balance?

Doing about 2hrs+ a day.. mixture of running, gym, swim and bike thoughtout the week.Usal annihilating long ride at the weekend.

Try to mix it up as I suck at them all.

Might be im just not getting enough sleep tho as Im doing it all before and after work.