I also notice almost every deposit has a bonus attached, which is another thing that does not help.
I would also say that your deposits are generally quite small, and you bet at max 60c per spin....this is another reason you may seldom arrive at a withdrawable amount. Unfortunately, as a rule you have to bet big to win big, so it really depends on what your expectations are in that regard and what you consider to be a 'decent' cashout amount e.g. If you deposit $25, and get it up to $150 or even $100 that is 4x your money which is a good return (it is also 4 more deposits), however if you deposit $100 then obviously that amount would be pointless. Also, you cannot expect to win $1000's on small deposits....it is a very very uncommon experience.
A couple of tips:
1.Set yourself a realistic cashout point and stick to it - it will help you to make more withdrawals.
2. Decide whether you want longer play time or more cashouts i.e. if you want better cashout possibilities, do not take bonuses. If you want more time for your money, then take a bonus with each deposit.
3. Try different software for a while, or permanently. Some people seem to do better on one platform versus another. After all, it isnt like you could do any worse!