Here are some rules I think will benefit any Takeda player who's finding they're either going to loose a campaign or have lost one for next time. I wrote this in another thread but I think it would be more useful here for people who are perhaps struggling with Takeda
I felt the same way you did but on my third campaign I did a lot differently.
1. Never declare war on somebody in the early stages
2. Never break an alliance
3. Recruit and use Metsukes, Ninjas and Monks fully (if you're going into to battle, get them to inspire your troops, if you have to leave a fort ungarrisoned, get a metsuke+monk to watch over it.
4. Do NOT recruit a full samurai army to begin with, go with Ashigaru troops and use the spear wall formation that is so destructive. Take a few units of light cavalry and a good chunk of archers. They are cheap, effective and you're able to have 2-3 armies for the price of one full samurai army meaning you can fight on all fronts.
5. Fight your wars through diplomacy, get allies to break alliances, join the other side of the war, do trade embargos, offer hostages and marriages to cement new alliances. As Takeda, if you decide to not declare war on anybody, you will be at peace for a long time and this is all you can do pretty much. Wait for the right opportunity, don't be impatient.
6. Focus on defence and spears in the Bushido skills section and focus on Chi mostly for farming and diplomacy.
7. Use Vassals to block off areas between enemies to give you some breathing space and focus on another warfront.
You will struggle to begin with and will seem hopeless, but be the mountain and you will be the last one standing in a better position than the rest. I'm on my third campaign on hard carving up Eastern Japan as I will, taking out entire Samurai armies with Ashigaru troops.
If you come across multiple stack armies, get your ninjas and other agents stuck in. The Hojo were twice my size and power, but I allowed them to destroy the vassals I had put up dividing their stacks as I had wanted. I think sent in my ninjas to sabotage the armies (which make them unable to move for one turn).
I then moved in with my one Ashigaru army and using this technique (demoralising them with monks and assassinating their generals and using monks to inspire my own men). I wiped out 3-4 stacks of their armies and took half of their provinces (they were the major power in the area).
Takeda is certainly hard but its a campaign for the patient