Your options as far as I know are as follows:
1.find a pre trained model that was trained on data similar to yours, and then fine-tune it with your current dataset.
2.if there is no pretrained model in frist place, but there are datasets that are similar to your dataset, first train on that dataset and then use the pre-trained model for fine-tuning.
3.use data augmentation to increase the size of your dataset. ( you can at least double or quadruple it )
and for the data, you really need as much data as you can gather, when you are dealing with deeplearning methods, or you have a very high chance of overfitting.