Hey Lauraluvstomatoes, here's the deal. I volunteer at a few nursing homes in the area. I do not do tomatoes. I didn't particularly want to do tomatoes. They asked nicely so I did tomatoes. This year we started tomatoes inside back a few months ago. Helped pot up lots of tomatoes at several different local nursing homes. I'm pretty good with some plants but no skill set what so ever with tomatoes or veggies. opabinia51 created a tomato FAQ which I added the name of this site to the top and a big URL to the forums then I inserted all of his information on growing tomatoes and increased all the font so residents could read the type and closed by typing the above was compliments of opabinia51 of The Helpful Gardener. In other words, I took all his work as is and cut and pasted it into handouts that I passed out to all of the residents at all of the nursing homes.
Unfortunately, one of the nursing homes I volunteered at is a memory care unit. Their residents either forgot how many times they had watered their tomatoes or forgot to water them. I think just about every one of their tomatoes died. Fortunately, that nursing home is a memory care unit so when I went out and replaced every single drowned or dried out dead tomato plant with one that was alive from trays of tomato plants I bought at WalMart, all of the residents were happy that their tomatoes had done so well. There are times when bait and switch are appropriate. Their tomatoes were planted outside by the residents a few days after I swapped them out to turn over watering of them to the maintenance staff. Those are all doing fine now. The tomato plants at the other nursing homes were watered better but some of the residents took them back to their rooms to grow on their window sills. All kinds of different exposures based on what side of the building a bedroom was on. About a third looked really great, a third looked so so, and a third looked eh... I helped the people who had plants that looked "eh" to fertilize their plants and oh shock of all shocks... one night out in the ground and they looked like a million bucks the very next morning... yup, bait and switch again. I went over there at night and swapped out the "eh" looking tomato plants. I think all residents had a good time planting their seeds in little pots and then planting tomatoes outside in the ground so all of the tomato planting sessions were a good thing in my mind. And the few left over tomato seeds that I had planted, well... they're in tomato plant heaven. Somebody forgot to water them with all the plants around here.
So see, everybody did better than me.
I can't answer your questions on no blossoms or too much nitrogen but I personally have no qualms about re-potting most plants that don't look too happy into a fresh medium.