What you described about the multiple branches radiating around the trunk, just below where the trunk has been top cut, is a typical growth pattern for such drastic top pruning. All too often growers have already done such pruning to larger crape myrtles when they are shipped to the retail nurseries. Did your area get the recent days' hard freeze around the Easter holiday? If so the CM in question might have a lot of dead wood which needs to be pruned out. If such a freeze happened, watch the tree as its remaining buds leaf out again. Once the tree appears to be fully leafing out enough to look recovered from any winter or freeze damage; totally remove any trunks or branches which fail to releaf. Also from the trunks nearest your house, completely remove all the way to the trunk any branches in the canopy which you can clearly tell will grow to infringe on your roof. Throughout the following growing seasons feed the tree with slow release quality food, and after every week which fails to provide an inch of rain for the shrub, suppliment the tree with that much water. Over the summer let the tree bloom naturally, and do not prune off the resulting seeds in an effort to extend your bloom season to the first freeze of late fall or early winter. By letting the tree bloom by itself and by being patient if it seems to slow down in bloom presentation after the first bloom flush; the tree will be enabled to put forth effort into thickening its branches and developing its proper rooting perportions. After the tree goes dormant, depending on when temps drop low enough for that, consider the space which any branching from the trunks still invade your roof line. cut, at that time, each trunk, all the way down to the root ball, whose canopy clearly will grow to infringe on your roof line. Hopefully when you have accomplished all the above pruning you will end up with the best of either a one or three main leader trunks. Then, in early march of the next year, prune out again all brittle dead wood, brake off the remaining seed pods and their twigs. Then turn your focus onto any remaining radiating branches which are growing just beneath the previously described, chopped off trunks. Preserve only a flexible and clearly healthy branch which grows the most directly upward and toward the direction where you want the trunk to continue growing. Prune away any other branches which are growing around the trunk near the same level of the healthy upward growing branch you selected to retain. To repeat: the one branch you choose to keep growing off the end of such chopped off trunks should be the one out of the ratiating bunches which appeares to be growing most upright, and growing in the right direction for the retained branch to assume the role of developing into a continuation of the trunk. Hopefully each single branch you select to continue the remaining trunks are thick enough to survive the following winter freezes. If not you will need to wrap each and their tunks with cotton insulator wrap prior to each freeze. If the temps are forecast to drop down to a hard freeze than add bubble wrap around the cotton wrap. Just be sure to remove the plastic bubble wrap any time the temps rise back up above 33 F. degrees. The above advised action takes a lot of dilligent effort, so if you do not think the tree is worth the trouble, simply remove it, grind the stump and main roots and purchase a 10 to 15 gallon sized, 25 to 30 feet potential height grower Crape Myrtle which has not also already been such drastically top pruned-down by the grower. With any such new CM tree you plant in the area, make certain to plant it far enough from the house to prevent roof damage, and to also prune train it properly each year just as you first described above.

I saw them today at a local nursery, and loved them. Can they be shaped to three to four trunks or less, like a small tree?

I like crape myrtles but the flower mess all summer looks pretty bad on a sidewalk, just wanted to mention that after reading #5. I think a great small tree is the western redbud (Cercis occidentalis). You still might have some trouble with #5 due to the seed pods but no tree is perfect. Another tree I really like is trident maple but that may grow a little larger than what you want. Here is a link that might be useful: quick internet seach result for western redbud

I'm looking for something not much more than 12'. Originally I was looking for a weeping type of tree which my neighbor's brother has and she wanted the same tree. Sadly her daughter passed away and I offered to buy the tree in honor of her daughter but we have limited space. My neighbor thought her brother's tree was a weeping Cherry tree but I found that one to be too large, her brother's tree is only about 6 to 7 feet tall. Upon more research I thought it was a weeping Wisteria tree which would fit the description. But those trees are limited in nurseries and as far as the net I'm not comfortable buying trees from the sources I've found there. But my neighbor ultimately left it up to me as for the tree type so I went looking for a dwarf blue spruce tree, which I did find at a nursery called "Baby Blue Spruce" which reaches 10' in ten years according to the tag. However, I looked it up and several places suggested it gets from 30' to 60' tall! I also found Blue Wonder Spruce which would be the perfect fit but once again the only source is the net which I'm uncomfortable with as far as trees go. Finding the right tree and size has become challenging. The Crape Myrtles were another option and there are sources where I might purchase one online or at the nursery, but my neighbor wanted a tree and some of them look more like shrubs. Although she said that would be okay but I still wanted something more upright in tree form and something that's also compact enough for our area. The colors of interest are purples, lavender, pink and blue, thanks!