My tomatoes don't seem to be getting bigger!

If you don't have drainage, they could be drowning. Plants do go into shock sometimes from too much water. Also with rain and or overwatering, the plants get all their nutrients washed away. It will take some time if it lives to come back but tomatoes are pretty tough. Good luck!

yes, you can drill several holes about an inch or two from the bottom which will allow for draining. Ideally you want a few inches of rocks or pebbles at the bottom then soil. You'll still need to have a few drainage holes in the soil just above the rocks. This will allow root growth toward the water at the bottom without getting root rot.

First check for mites on the undersides of leaves. Does pot have good drainage? If not you'll get root rot. Tomatoes require almost daily watering.

When we have these heavy rains, it splashes dirt on the plants and causes early blight, which you'll see the bottom branches will turn yellow. putting plastic down helps to prevent this.

You also want to make sure you give your plants enough space to have air keep them dry. If you notice leaves with blight, cut them off to keep it from spreading to the rest of the plant.

Sounds like poor drainage.

As all tomato plants flowers that are to close together should be pinched off,bottom of the tomato plants should be pruned for air circulation.http://homeguides.sfgate.com/prune-early-girl-tomato-plants-39288.html