DD was the same who is now 5.4 months, it was agony. She has only very recently learned to play alone for up to 30 mins, 2 or 3 times a day. Here is what we did;
Ask her first thing in the morning what SHE would like to do. I would say, here are the 4 choices, you pick 2 of those & lets have lots of fun doing what you choose.
I then REDUCED the amount of time I spent entertaining her.
So her day would be 1 activity (music class, swimming, cycling e.t.c), followed by a walk or trip to the park, lunch out. Then home and its 'quiet time' in the afternoon (usually 3pmish). During this half hour I would suggest that she plays with her toys. If (when) she moaned about being bored I told her we went out and did the fun things she asked to do today so this is mummy's time. She would understand as my tone was kind but firm. Then its Tea, 'quiet time' again, bath, reading, bed.
If Im doing the housework during 'quiet time' and she badgered me to play with her, I'd smile sweetly and ask if she would like to help me dry dishes or put out the washing. I genuinely would love help but the answer is a straight NO (followed by running off to plain independently in silence).
Slowly . . .and I us that phrase lightly, it worked! She seems to understand that she has her time and adults have their time. It is a gradual build up of minutes that becomes 10, then 12, then 3, then 30 - ta da!!! Job done. Ive seen more creativity in her during these independent time than ever before. She is learning to find her own way which is perfect.
Do you have a Garden? Spring is here so a trampoline, tent, bike, water play, football goal so your DS can practice kicking in the net? if you are able to.
Best of luck X