More thoughts.
Your genetics determine your potential. Well genetics and doping. But genetics. You mention not being a strong climber. I understand - at 5'7" and 103 lbs I couldn't climb (as a Junior racer). I certainly can't climb at 170 and the same height. I've had people ask me if I had a mechanical because I was climbing so slowly (and I was actually pleased with how fast I was going until the guy caught me and asked if I needed help).
Fast twitch and slow twitch. You don't really change them. At 103 lbs I thought I was a climber but I couldn't climb. I didn't think I was a sprinter because I was way too skinny, way too weak (bench 90 lbs), but I'd accidentally (in my mind) win group ride sprints and even a couple races. Only after another year of racing (where I won a few races in sprints and failed when I tried to break away and got shelled on pretty much every hill) I decided that my sprint wins weren't gifts from everyone, that other riders were trying, etc.
If Sunday is an important day then make Monday a hard day too. Do your steep hill intervals etc.
Diet-wise I focus on diet and basically ignore training. The training happens later and the weight you lose is much more significant than any minor fitness gains you can get through training. I thought of this while I was on the trainer just now. I rode really hard for me, 160 watts avg for 2 hours. That's just slightly below race pace for me in a Cat 3 or M40+ race or even the Cat 2 Tour of Somerville. I was watching a Tour DVD while I rode. They discussed holding 325, 387, and 425 watts for an hour at a time.
I'll never do 425 watts for an hour. I could be doped to the gills but I won't improve my approximate 210w FTP by 100%.
Anyway back to my 210w FTP.
At 215 lbs, 97.6 kg, I can do a long climb putting down a massive 2.15 w/kg for an hour aka Functional Threshold Power aka FTP.
At 180 lbs, 81.7 kg, I can do 2.57 w/kg.
At 155 lbs, 70.4 kg, I can do 2.98 w/kg. This, by the way, is apparently the level of a low level amateur racer, i.e. a Cat 5. I upgraded to Cat 2 on this w/kg.
Here's a chart that sort of illustrates all that.
At 215, to climb as well as a 155 lbs me, I'd have to increase my FTP to 290w, an 80w or approximately 40% increase in power.
At 180, to climb as well as a 155 lbs me, I'd have to increase my FTP to 243w, a 33w or approximately 15% increase in power.
If you're already training pretty hard, and it sounds like you are, you're going to be pretty close to your realistic FTP max. I mean, okay, if you did some insane hours you might increase your FTP a bit but my FTP basically didn't change in my best ever year of racing in 2010, and it's remained constant through the next 2 years. I figure there's a 5% fluctuation, like 210 to 220w (10 watt difference, 5%).
Realistically it'll be hard to increase your FTP by more than, say, 15 or 20%. For me that would mean a 42-44 watt increase, a huge increase based on my low numbers.
The reason this is significant is that unlike a car you can't just jam a turbo on your body/legs/engine or nitrous or a supercharger or chip it or whatever. Your engine is pretty set, +/- a very small number. That number limits everything you can do.
That is why weight loss is so significant. It radically alters your power to weight ratio and it's the only way to radically alter that ratio. It take some discipline to lose weight, some to keep it off. It's not fun. You skip cheese and beer and cookies and deserts and any alfredo sauce etc etc etc. But when you lose weight it's huge, just huge. It's like increasing your power 10 or 15 or 40%, something that would take oodles of training time, much more time than it takes to lose a small but significant amount of weight.
I suppose you could lose 5 lbs off your bike but that's not that much compared to what you can lose from your body. I went to a 1-1.5 pound heavier bike when I lost all that weight, because of fit reasons, but my overall rider/bike combined weight was significantly lower than the prior year.
My lighter weight affected me even in flat races - I didn't have to accelerate a rider with a grill tank hanging off his butt, I just had to accelerate the rider. Do a few jumps and the efforts really add up. My peak numbers accelerating out of turns dropped about 200-300w when I was lighter, ditto my numbers on short sprint type hills. I didn't think more weight would affect me that much but it did.
If you want to estimate your power you can join Strava and climb the longest climb you can find. Strava, based on your weight etc, will be pretty close to your wattage on that climb. If it's a 20 minute climb and you're totally crosseyed at the top then divide that wattage by 1.05 and that's your FTP. There are other ratios but I don't remember them. Strava doesn't count wind resistance well so its estimated watts really only works on steady and significant hills. To give you an idea some of my rides get me 400w estimates from Strava, a wattage level I can barely hold for a minute.
Once you have your power you can start plugging in numbers. Realistic weights. Lose 10 lbs? 20 lbs?
Try going faster up the same hill. Check out the wattage difference. Think about how fast you have to go to get to the wattage number you need to equal losing 10 lbs. All of a sudden dieting for 5 weeks seems pretty easy.
Those are some thoughts I had on the trainer (I had to do the math after I got to the computer).